Osteoinductive putties and methods of making and using such putties

ABSTRACT

The present disclosure relates to osteoinductive putties and other implantable compositions for repair of bone defects and other medical uses. Specifically, the technology pertains to carriers for use in implantable compositions, such as osteoinductive putties. The osteoinductive putties are made entirely from donor tissue such as demineralized bone matrix, and the putties have excellent physical properties. The present disclosure relates to osteoinductive putties, carriers, compositions, implants, kits, methods of making and methods of using any of the foregoing.

CROSS REFERENCE TO RELATED APPLICATIONS

This application relates to and claims priority benefits from U.S.Provisional Patent Application Ser. No. 61/008,887, filed Dec. 21, 2007,entitled “Osteoinductive Putties and Methods of Making and Using SuchPutties”. The '887 provisional application is hereby incorporated byreference in its entirety.

FIELD OF THE INVENTION

The technical field involves putties and other implantable compositionsfor repair of bone defects and other medical uses. Specifically, thetechnology pertains to an osteoinductive putty made entirely from donortissue such as demineralized bone matrix and having desirable physicalproperties. The present disclosure relates to osteoinductive putties,carriers, compositions, implants, kits, methods of making and methods ofusing any of the foregoing.

BACKGROUND OF THE INVENTION

Various compositions have been used to repair bone defects and otherdamaged tissues. For example, compositions are available to promote orsupport new bone growth and/or to provide active agents that induce newbone growth. Demineralized bone matrix (DBM) and bone morphogeneticproteins (BMPs) are two agents that have been used to induce bonegrowth.

DBM is bone that has been demineralized at least partially. Bone can bedemineralized in a variety of ways, such as by exposure to an acid, toremove at least some of its natural mineral content. DBM typicallyincludes highly cross-linked collagen as well as other proteins, such asBMPs and other growth factors. DBM alone, or with one or more addedBMPs, or other growth factors or with some combination thereof can beused to treat bone defects.

DBM and BMPs can be used in combination with carriers in order to createan implantable material. A number of different carriers have been usedin the past with varying degrees of success. Previously used carriersinclude materials such as collagen sponges, glycerol, synthetic polymersand hydrogels (e.g., gelatin and chitosan).

As an example, GRAFTON® is a commercially available product comprisingDBM suspended in a polyhydroxy compound (e.g. glycerol) or estersthereof, optionally including various other ingredients, such asgelatin.

BRIEF SUMMARY OF THE INVENTION

The present invention provides novel carriers for use in implantablecompositions, such as in osteoinductive putties. The present carriershave excellent physical properties, such as excellent stability,cohesiveness, flowability, moldability, extrudability, resistance toirrigation, and/or cohesion in solution. In various embodiments, thecarriers include a mixture of collagen fragments. In some embodiments,the carriers comprise a mixture of collagen fragments having asubstantially uniform molecular weight distribution within the range offrom about 45 kDa (kilodaltons) to about 66 kDa, and/or from about 29kDa to about 97 kDa. Alternatively or additionally, the carrierscomprise a mixture of collagen fragments having a sodium dodecyl sulfatepolyacrylamide gel electrophoresis (SDS-PAGE) profile that does notinclude a banded region between about 45 kDa and about 66 kDa, and/orbetween about 29 kDa and about 97 kDa. Alternatively or additionally,the carriers comprise a mixture of collagen fragments having an SDS-PAGEprofile substantially the same as shown in Lane C of any of FIGS. 2Athrough 2D. Alternatively or additionally, the carriers comprise amixture of collagen fragments having an SDS-PAGE profile having adiscrete band between about 15 kDa and about 20 kDa.

The present carriers have superior physical properties compared to othermaterials employed as carriers. Many of these properties are due to thefact that the carriers are not hydrogels or do not form a hydrogel evenafter the passage of time. In some embodiments, the carriers and puttiesdo not have a measurable Bloom strength (are not a gelatin) and/or areprovided as a viscous liquid.

The present invention also provides novel osteoinductive putties. Theosteoinductive putties include a carrier, such as the carriers describedabove, and an osteoinductive substance, such as demineralized bonematrix or one or more bone morphogenetic proteins. The present inventionprovides osteoinductive putties comprising an osteoinductive substance,and a carrier comprising a mixture of collagen fragments, wherein theputty is extrudable, moldable, resistant to irrigation, and maintainscohesion in solution. The putty can be adapted for packing into a bonedefect, such as a spinal or vertebral defect. Various embodiments of theosteoinductive putties can remain extrudable, moldable, resistant toirrigation and/or resistant to dissolution (cohesive in solution), andretain their osteoinductive properties, even following extrusion,forming, molding or shaping, and after terminal sterilization andextended storage (for example, sterilization by gamma irradiationfollowed by storage overnight or longer, or for at least one, two orthree months, or up to six months or one year) in a sealed package. Insome embodiments, the osteoinductive substance is demineralized bonematrix, and the demineralized bone matrix and the carrier are derivedfrom the same donor and/or a single collagen source (such as an initialDBM sample), and/or the demineralized bone matrix and the carrier areboth derived from cortical bone, cancellous bone, trabecular bone, orcombinations thereof.

The present invention also provides novel methods of making a carrierfor use in an implantable composition. The methods include the steps ofproviding a collagen source comprising collagen, such as fibrillarcollagen, and combining the collagen source with a denaturing solutionto create a collagen source mixture. For example, fibrillar collagenincludes Type I collagen and Type II collagen. The collagen sourcemixture is heated to a temperature and for a time sufficient to producea carrier having the desired molecular weight distribution and/or thedesired physical properties as described herein. For example, thecollagen source mixture can be heated at about 120° C. for about 90minutes. The methods can also include drying and/or freezing thecollagen source mixture (such as by lyophilization), so that a carrieris provided in dry form. The methods can also include the step ofneutralizing (which encompasses partially neutralizing or fullyneutralizing) the collagen source mixture after heating by adding a baseor an acid.

The present invention also provides novel methods of making anosteoinductive putty. The methods include the steps of providing anosteoinductive substance, a liquid medium, and a collagen source, suchas a collagen source comprising preferably Type I or Type II collagen.The methods also include combining the collagen source with a denaturingsolution to create a collagen source mixture. The collagen sourcemixture is heated at a temperature and for a time sufficient to producethe desired carrier. The carrier is combined with the osteoinductivesubstance and the liquid medium in relative amounts sufficient to form aputty. After heating, the denatured collagen source mixture can befrozen and/or dried (such as by lyophilization) to form a dry carrier.

The present invention also provides novel kits comprising anosteoinductive putty in a package. The kits include an osteoinductiveputty comprising an osteoinductive substance, a carrier comprising amixture of collagen fragments, and a liquid medium. The kits alsoinclude a package, such as a syringe. In such kits, the osteoinductivesubstance and carrier are preferably sterilized after being sealed inthe package, and the putty is ready to use (RTU) upon removal from thepackage. In various embodiments, the putty is stable in the sealedpackage for at least about one week, or at least about one month, or atleast about six months, or at least about twelve months, or at leastabout 2 years, or at least about 3 years, or another length of time.Even after extended storage (for example, overnight or longer, or for atleast one, two or three months, or up to six months or at least one, twoor three years) in a package that is moisture resistant (e.g.,hermetically sealed), preferred embodiments of the osteoinductive pasteremain extrudable, moldable, resistant to irrigation and cohesive insolution, and/or capable of packing into a bone defect site, whileretaining their osteoinductive properties.

The present invention also provides novel methods of treating a subjectin need of treatment for a bone defect. The methods include implantingan osteoinductive putty into a bone defect, wherein the putty comprisesan osteoinductive substance, a liquid medium, and a carrier as describedherein. In some embodiments, the osteoinductive putty is directlyinjected from a syringe into the subject. The methods of treatment canalso include the step of irrigating the bone defect after implanting theosteoinductive putty without washing away a substantial amount of theosteoinductive putty.

The present invention also provides novel implantable compositionssuitable for use in making formed implants. The present implantablecompositions have desirable physical properties, such as excellenthandling and cohesion in solution. In various embodiments, theimplantable compositions include a mixture of collagen fragments. Theimplantable compositions are produced by combining a collagen sourcewith a denaturing solution to create a collagen source mixture. Thecollagen source mixture is heated to a temperature and for a timesufficient to produce an implantable composition suitable for making aformed implant. For example, the collagen source mixture can be heatedat about 120° C. for about 60 minutes or at about 100° C. for about 90minutes or longer.

The present invention also provides novel formed implants. The formedimplants include an implantable composition, such as the implantablecomposition described above, and an osteoinductive substance. The formedimplants are made by combining an osteoinductive substance, a liquidmedium, and the implantable composition described above in relativeamounts sufficient to form a formed implant.

These and other features of the present invention are discussed orapparent in the following detailed description.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIGS. 1A through 1C are photographs of putties that have been extrudedfrom a syringe having a narrow tip. The different putties comprisecarriers prepared from demineralized bone matrix at different processingtemperatures.

FIGS. 1D and 1E are photographs of putties that have been extruded froma syringe having a wide tip, and molded by hand into a rough sphere. Thedifferent putties comprise carriers prepared from demineralized bonematrix at different processing temperatures and different processingtimes.

FIG. 1F is a photograph of a putty made from demineralized bone matrixheated to 120° C. temperature for 90 minutes, mixed with activedemineralized bone matrix and water, then extruded and molded by handinto a ball shape.

FIG. 1G is a photograph of a putty made from demineralized bone matrixheated to 120° C. for 90 minutes, mixed with active demineralized bonematrix and water, then extruded and placed on a glass slide to be testedfor irrigation resistance.

FIG. 1H is a photograph of a putty made from demineralized bone matrixheated to 120° C. for 75 minutes, mixed with active demineralized bonematrix and water, then extruded and molded by hand into a ball shape.

FIG. 1I is a photograph of a putty made from demineralized bone matrixheated to 120° C. for 75 minutes, mixed with active demineralized bonematrix and water, then extruded and placed on a glass slide to be testedfor irrigation resistance.

FIG. 1J is a photograph of a putty made from demineralized bone matrixheated to 120° C. for 90 minutes, mixed with active demineralized bonematrix and water, then extruded and molded by hand into ball shape, aswell as placed on a glass slide to be tested for irrigation resistance.

FIG. 1K is a photograph of a syringe loaded with putty that has been setup for an extrusion test in the Instron force testing machine.

FIG. 1L is a photograph of the apparatus used to test extruded putty forirrigation resistance, wherein a lavage pump is set to impinge upon amicroscope slide, directly adjacent to the adhering putty sample.

FIG. 1M is a photograph of the front view of the water bath andapparatus used to test extruded putty for cohesion in solution(dissolution).

FIG. 1N is a photograph of the top view of the water bath and apparatusused to test extruded putty for cohesion in solution.

FIG. 1O is a photograph of one putty made from demineralized bone matrixheated to 120° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled A3 in thephotograph), and another putty made from demineralized bone matrixheated to 135° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled S3 in thephotograph).

FIG. 1P is a photograph of one putty made from demineralized bone matrixheated to 118° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled W3 in thephotograph), and another putty made from demineralized bone matrixheated to 120° C. for 180 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled U3 in thephotograph).

FIG. 1Q is a photograph of one putty made from demineralized bone matrixheated to 118° C. for 90 minutes, mixed with active DBM and water(containing 50% more water than the putty shown in FIG. 1P), thenextruded and molded by hand into a ball shape (labeled W3X in thephotograph), a second putty made from demineralized bone matrix heatedto 135° C. for 75 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled T3 in thephotograph), and a third putty made from demineralized bone matrixheated to 115° C. for 90 minutes, mixed with active DBM and water(containing 50% more water than the putty shown in FIG. 1R), thenextruded and molded by hand into ball shape (labeled V3X in thephotograph).

FIG. 1R is a photograph of one putty made from demineralized bone matrixheated to 115° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled V3 in thephotograph), and another putty made from demineralized bone matrixheated to 100° C. for 90 minutes, mixed with active DBM and water, thenloaded in a syringe, which failed to extrude from the syringe (labeled13 in the photograph).

FIG. 1S is a photograph of four putties, each processed for 90 minutesat a different temperature, and each mixed with a higher concentrationof water (about 32% more water than the putties shown in previousFigures). The first is a putty made from demineralized bone matrixheated to 100° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled I4 in thephotograph). The second is a putty made from demineralized bone matrixheated to 110° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled X4 in thephotograph). The third is a putty made from demineralized bone matrixheated to 120° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled A4 in thephotograph). The fourth is a putty made from demineralized bone matrixheated to 135° C. for 90 minutes, mixed with active DBM and water, thenextruded and molded by hand into ball shape (labeled T4 in thephotograph). It was noted following completion of testing that thesample labeled as T4 in FIG. 1S was actually labeled and tested as S4 inExamples 17, 18, and 19.

FIGS. 2A through 2H set forth SDS-PAGE profiles (shown by Western blotanalyses) of several putties and carriers. Some of the carriers weregelatins while other carriers were putties made from DBM at differenttemperatures.

FIGS. 3A through 3F set forth High Performance Liquid Chromatography(HPLC) analyses of several putties and carriers. Some of the carrierswere gelatins while other carriers were made from DBM at differenttemperatures.

FIGS. 4A and 4D set forth dynamic viscosity analyses of putties andcarriers prepared from demineralized bone matrix at differenttemperatures.

DETAILED DESCRIPTION OF THE INVENTION

The present disclosure relates to novel osteoinductive putties, carriersfor such putties, compositions related to such putties, implantsincluding such putties, kits for the use of such putties, and methods ofmaking and using any of the foregoing. The osteoinductive puttiescomprise an osteoinductive substance, a liquid medium, and a carrier asdescribed herein. The term putty includes pastes, gels, viscoussuspensions, solutions, liquids, and mixtures, and generally refers toany material that is not completely solid. The present putties can be inthe form of a viscous mixture or liquid, as described in more detailbelow. The present disclosure also relates to novel formed implants,implantable compositions for such implants, compositions related to suchimplants, kits for the use of such implants, and methods of making andusing any of the foregoing. Although certain parameters are used asexamples, the current disclosure should not be viewed as limited to suchspecifics.

An osteoinductive substance has at least some ability to promote orassist in bone growth, such as the ability to recruit and transformcells from the host which have the potential for repairing bone tissue.For example, demineralized bone matrix and osteoinductive proteins suchas bone morphogenetic proteins (BMPs) are considered to beosteoinductive substances. Autograft, allograft, xenograft orrecombinantly produced BMPs or other naturally produced or recombinantgrowth factors are also considered osteoinductive substances.Osteoinductive proteins include some of the proteins in the transforminggrowth factor-beta (TGF-beta) superfamily of proteins, which includesthe bone morphogenetic proteins (BMPs), activins and inhibins.

The present osteoinductive putties and compositions can beosteoconductive as well as osteoinductive. When a substance isosteoconductive, it has at least some ability to provide support for thegrowth of new host bone. For example, demineralized bone matrix, intactbone allografts, calcium phosphate and hydroxyapatite are considered tobe osteoconductive substances. The present osteoinductive putties andcompositions can also be osteogenic as well as osteoinductive. When asubstance is osteogenic, it includes cells such as osteoblasts that canform bone, or stem cells that can be turned into bone-forming cells. Thepresent putties and compositions may also be provided innon-osteoinductive forms, and have utility as an inert osteoconductivecarrier in a variety of applications. For example, a therapeuticnon-osteoinductive putty may be implanted to promote healing at a bonysite alone or in conjunction with other osteoinductive therapies, or ina non-bony site to promote, direct or control fibrous or cartilaginoushealing, ingrowth or guided regeneration. Unless otherwise noted, allreferences to osteoinductive putties throughout this specification mayalso be applied to osteoconductive or inert non-inductive putties. Thecurrent putties may additionally be used or adapted for use in dentalregeneration and cartilage regeneration applications.

Methods of Making Demineralized Bone Matrix

Demineralized bone matrix (DBM) is the product of removing at least someof the mineralized component from bone but retaining collagen andnoncollagenous proteins, including growth factors. DBM can be made froma number of different starting materials, such as natural tissues orsynthetic materials. For example, DBM can be made from human bone,non-human bone or a mixture thereof. DBM can be made from various typesof bone, such as cortical, cancellous, trabecular, or mixtures thereof.DBM can take various physical forms. For example, DBM can be in the formof blocks, strips, cylinders, chips, cubes, shavings, particles orpowders. When DBM is formed into chips, shavings, particles or powders,it is particularly desirable to combine the DBM with some sort of puttyor other carrier to aid in handling and delivery to the desiredtreatment site.

Source materials for the DBM and/or collagen source can be autograft,allograft, xenograft, or transgenic materials. The use of autograftmaterial (where the patient's own body provides the source for thematerial), allograft material (where another human provides the sourcematerial), xenograft material (where a different species provides thesource) or transgenic material bone (where a transgenic species providesthe source) is well known in both human and veterinary medicine.Xenograft or transgenic materials may require further treatments (e.g.chemical fixation) to minimize the level of immunogenicity in thematerial.

DBM is typically derived from bone from human donors. Alternatively, DBMis derived from bone from animal donors, such as porcine, ovine orbovine bone. Donated bone is removed and initially processed asepticallyand/or treated to kill any infectious agents. The bone is thenoptionally particulated by milling or grinding and then the mineralcomponent is extracted (e.g., by soaking the bone in an acidicsolution). Alternatively, some or all of the calcium extraction may beperformed prior to milling, grinding or shaping the bone, with thesoftening of the demineralized portion of the bone resulting in changesto stiffness and machineability. The remaining matrix is malleable whenhydrated, and can be further processed and/or formed and shaped forimplantation into a particular site in the recipient. The DBM can beprocessed into the form of blocks, strips, cylinders, chips, shavings,cubes, particles, or powders.

Tissue from a single donor (allograft or xenograft) is preferred due tofavorable regulatory status as a minimally manipulated tissue product aswell as reduced health risk and disease transmission risk as compared totissue from multiple sources. Donor to donor variability exists in mostforms of tissue implants, including DBM. Osteoinductivity andinflammatory response may vary from one donor to the next. Due to thisvariability, osteoinductivity testing is often a beneficial first stepin selecting donor tissue for processing into any potentiallyosteoinductive composition.

Demineralized bone matrix prepared in this manner typically contains avariety of components including proteins, glycoproteins, growth factors,and proteoglycans. Following implantation, the presence of DBM inducescellular recruitment to the site of injury. The recruited cells mayeventually differentiate into bone forming cells. Such recruitment ofcells leads to an increase in the rate of healing and, therefore, tofaster recovery for the patient. Accordingly DBM is considered to be anosteoinductive substance or material.

There are a number of different methods of producing DBM from thevarious starting materials. DBM is commonly prepared by acid extractionof bone, resulting in loss of most of the mineralized components butretention of collagen and noncollagenous proteins. Other methods includealkaline extraction of bone. Any process known to those familiar withthe technology can be used. Some specific processes are discussed belowmerely for exemplary purposes.

In one method of demineralization, a section of source bone is treatedto remove soft tissue, including marrow and blood, and is thenperforated to form a multiplicity of holes of desired size, spacing, anddepth. The perforated bone section is then immersed and demineralized inan acid bath (e.g., 0.6 Normal (N) hydrochloric acid (HCl)), and isfurther treated in a defatting solution to remove remaining marrow andintra-matrix cells. Following the perforating and defatting steps, thegrafts can be freeze-dried and stored in sterile bags at conventionalroom temperature for periods of up to one year and perhaps longer priorto implantation or prior to use in the present methods of making acarrier, osteoinductive putty, or other implantable compositions.

In another method of making DBM, DBM is prepared by first removing allsoft tissue and washing the bones in sterile deionized water. Thecleansed bones are then extracted in a chloroform-methanol mixture,dried overnight, milled, sieved and decalcified in 0.6 N HCl for threeto four hours. The resultant powder is rinsed with sterile deionizedwater to bring the pH to 3.5 or above and then lyophilized.

In yet another method of making DBM, DBM is prepared by soaking the bonesegments for several minutes in a container with enough sterile ethanolto cover the tissue. The bone segments are milled and placed in a sieve.The milled bone material is cleaned with hydrogen peroxide, removed andrinsed with sterile water. The rinsed bone powder is added to sterileethanol. The bone powder is then dried. The dried bone powder istransferred to the demineralization process. The bone powder is mixedwith 0.6 N HCl until most of the mineral content is removed from thebone. The bone powder can be left for a longer period of time to fullydemineralize the bone powder.

Other Osteoinductive Substances and Additives

In addition to or instead of DBM, other osteoinductive substances can beincluded in the present osteoinductive putties. Autograft, allograft,xenograft, transgenic or recombinantly produced osteoinductivesubstances can be employed. Preferably, natural (e.g., autograft,allograft or xenograft) osteoinductive substances can be employed, evenmore preferably those that are isolated or purified from naturaltissues. BMPs or other naturally produced or recombinant growth factorsand proteins, or fragments thereof having osteoinductive activity, canbe included as the osteoinductive substance. Preferably, naturallyproduced growth factors and proteins or fragments thereof can beemployed. Osteoinductive proteins include some of the proteins in thetransforming growth factor-beta (TGF-beta) superfamily of proteins,which includes the bone morphogenetic proteins (BMPs), activins andinhibins. In some embodiments, the osteoinductive substance includes atleast one growth factor selected from the BMPs which have osteoinductiveactivity, and other growth and differentiation type activities. TheseBMPs include BMP proteins BMP-2, BMP-3, BMP-4, BMP-5, BMP-6, BMP-7,BMP-9 (GDF-2), BMP-10, BMP-12, BMP-13, BMP-15, BMP-16, BMP-17, andBMP-18. BMPs may exist as dimers of the same monomeric polypeptides(homodimers) held together by hydrophobic interactions and/or one ormore disulfide bonds or other molecular bonds. However, BMPs may alsoform heterodimers by combining different monomers (for example, a BMP-6monomer associated with a BMP-2 or BMP-7 monomer). In the presentputties and compositions, the osteoinductive substance can be a dimer(such as a homodimer or heterodimer) that comprises one or more of theforegoing BMPs or another osteoinductive protein, or a fragment thereofhaving osteoinductive activity. For example, BMPs can be provided in amixture of homodimers and heterodimers. Alternatively recombinantheterodimeric BMP proteins can be employed. Heterodimeric BMP proteinsare disclosed in U.S. Pat. Nos. 6,593,109 and 7,300,772 (GeneticsInstitute, Inc.) as being useful for treating bone defects, healing boneinjuries and in wound healing in general. For example, the heterodimersmay comprise a protein or fragment of any of the foregoing BMPsassociated with a protein or fragment of another BMP. Otherosteoinductive proteins include some of the proteins referred to asGrowth and Differentiation Factors (GDFs), such as GDF-3, GDF-5, GDF-6,and GDF-10. Other osteoinductive substances are known to those familiarwith the orthopedic field or those familiar with the mechanisms of bonegrowth, regeneration and healing. The osteoinductive putties can includeother components. For example, one or more salts or ions can be includedin the putties. Salts comprising calcium and/or phosphate can beincluded, such as calcium chloride, calcium sulfate, calcium phosphate,and calcium hydroxyapatite.

In addition to the osteoinductive substance, osteogenic substancesand/or osteoconductive substances can also be added to the presentosteoinductive putties. Examples of additional osteoconductivesubstances include allograft or xenograft bone (e.g. cortical cancellouschips), calcium phosphate and hydroxyapatite. Examples of additionalosteogenic substances include osteoblasts, stem cells or multipotentadult progenitor cells (MAPCs) that can be turned into bone-formingcells.

Free radical scavengers can also be added to the DBM, osteoinductivesubstance, carrier, or osteoinductive putty in order to increase storagetime. Free radical scavengers are thought to increase storage time bypreventing or reducing oxidation. Examples of free radical scavengersinclude, but are not limited to, vitamin C, vitamin E and beta-carotene.

Methods for Making Carrier

For the present methods, the carrier can be produced from a collagensource. Collagen sources (e.g., tissues comprising fibrillar collagen,such as Type I or Type II collagen) include demineralized bone matrix(DBM), whole bone, bone chips, bone power, skin, tendons, ligaments,meniscus, and cartilage. Preferably the collagen source is or is derivedfrom a natural tissue or otherwise naturally produced (e.g., fromautograft, allograft or xenograft sources), but it is contemplated thatthe collagen source may be a synthetic material, such as collagen thatis recombinantly produced. In some preferred embodiments, an amount ofDBM is divided and a first portion is used to produce a collagen sourceand a second portion is used as the osteoinductive substance. Tissuescomprising Type I collagen can be from human or non-human (autograft,allograft, transgenic and/or xenograft) sources, similar to the DBM. Amixture of various Type I collagen-containing tissues can also be usedas the collagen source. Tissues comprising Type II collagen can be fromhuman or non-human (autograft, allograft, transgenic and/or xenograft)sources, such as cartilage. A mixture of various Type IIcollagen-containing tissues can also be used as the collagen source. Amixture of various Type II and Type I collagen-containing tissues canalso be used as the collagen source.

The collagen source can be in any physical form, such as bone shafts,whole or partial tendons, sections of dermis or other connectivetissues, bone blocks, strips, cylinders, chips, cubes, shavings, fibers,particles, or powders. The use of smaller particles may result in higherdissolution of the collagen source during a denaturation process. Thecollagen source can optionally be mechanically processed to achieve amore uniform, consistent, or homogeneous makeup. The mechanicalprocessing can occur prior to or after demineralization where thecollagen source undergoes demineralization. If the collagen source isderived from bone, such as DBM, various types of bone can be used. Forexample, cortical, cancellous, trabecular or mixtures thereof can all beused.

In some embodiments, a carrier is made by subjecting DBM to adenaturation process at a suitable temperature, for example 120° C. orhigher, for a suitable time period, for example 90 minutes or longer. Itis theorized that the denaturation process yields a product in which aportion of the collagen in the DBM is denatured, a portion of thecollagen in the DBM is fully intact and a portion of the collagen in theDBM is denatured and hydrolyzed. Collagen can be hydrolyzed to varyingdegrees by the denaturation processes described herein, providingcollagen fragments of varying molecular weights.

Denaturing refers to separating strands of collagen. Collagen is themain protein of connective tissue in animals. The tropocollagen orcollagen molecule subunit is made up of three polypeptide strands. Thereis some covalent crosslinking within the triple helices, and a variableamount of covalent crosslinking between tropocollagen helices, to formthe different types of collagen found in different mature tissues. Inbone, collagen triple helices lie in a parallel, staggered array.Collagen gives bone its elasticity and contributes to fractureresistance.

Hydrolyzing refers to breaking bonds between individual amino acids,which results in shorter strands. In various embodiments of the presentmethods, DBM subjected to a denaturation process undergoes at least somedenaturation of the strands of the tropocollagen, and in someembodiments, hydrolyzation of bonds within some strands. Treatingcollagen under different conditions can lead to different compositions,with different degrees of denaturing and hydrolyzing leading todifferent mixtures of collagen fragments.

Various gelatins have previously been used as carriers forosteoinductive agents. Gelatin is formed from collagen which has beendenatured and hydrolyzed to some extent. In general, the molecularweight of the fragments present in gelatins are similar in size. Due totheir similarity of size, these particles can then line up to form aninterconnective matrix of hydrogen bonds. Such a structure is typicallyconsidered a hydrogel.

In the present disclosure, denatured collagen refers to collagen inwhich the strands of the tropocollagen molecule are at least partiallyseparated. Intact collagen refers to collagen in which the strands ofthe tropocollagen molecule are not separated. Hydrolyzed denaturedcollagen refers to collagen in which the strands of the tropocollagenmolecule are at least partially separated and at least partially brokeninto shorter strands. In the present disclosure, hydrolyzed denaturedcollagen is not limited to particles that are similarly sized as ingelatin. The hydrolyzed denatured collagen of the present carriers willgenerally have some particles, fragments or strands that are smallerthan those in a gelatin.

As one example of a denaturation process, a collagen source such as DBMis exposed to a denaturing solution. In the present disclosure, the termdenaturing solution refers to the solution used in the processesdescribed herein, and generally does not require that the solutionindependently cause denaturation outside the processes described herein.The denaturing solution can be selected from the group consisting of anacidic solution, a basic solution, or an enzymatic solution. The acid,base, or enzyme can be combined with water or a solution comprisingwater and some other component. For example, the other component couldinclude a component normally found in animal blood serum (e.g., sodiumchloride, potassium phosphate, sodium bicarbonate, or the like). Thedenaturing solution can be selected from solutions other than saline orwater alone, though the denaturing solution can include water and/orsodium chloride in addition to an acid, a base or an enzyme.Alternatively or additionally, the denaturing solution can include anorganic solvent such as ethylene glycol or glycerol. A potentialadvantage from using such a solvent is that the boiling temperature ofthe denaturing solution can be increased.

Suitable acidic denaturing solutions include hydrochloric acid (HCl),hydroiodic acid (HI), sulfuric acid (H₂SO₄), or another inorganic acid.Other acidic solutions can include acetic acid (CH₃COOH), aspartic acid(HO₂CCH(NH₂)CH₂CO₂H), lactic acid (C₃H₆O₃), fumaric acid(HO₂CCH═CHCO₂H), sorbic acid (C₆H₈O₂) and glutamic acid (C₅H₉NO₄), oranother organic acid. A suitable concentration of acid can be selected.In some embodiments, the concentration of acid is from about 0.001 toabout 5 N, alternatively from about 0.01 to about 1 N, alternativelyfrom about 0.025 to about 0.1 N, or alternatively about 0.05 N. In someembodiments where an acidic HCl solution is used, the denaturingsolution has a concentration from about 0.025 to about 0.1 N, oralternatively about 0.05 N. The concentration of acid may be selectedbased on the type of acid used and its dissociation constant.

Suitable basic denaturing solutions can include alkali metal base oralkali earth metal base, such as sodium hydroxide (NaOH), potassiumhydroxide (KOH), zinc hydroxide (Zn(OH)₂) or calcium carbonate (CaCO₃).In some embodiments, the concentration of base is from about 0.001 toabout 5 N, alternatively from about 0.01 to about 1 N, alternativelyfrom about 0.025 to about 0.1 N, or alternatively about 0.05 N.

Suitable enzymatic denaturing solutions include bacterial collagenases(such as those collagenase preparations available from WorthingtonBiochemical Corporation, Lakewood, N.J.) and those mammalian matrixmetalloproteinases that are active toward collagen (such as MMP-1).Enzymatic denaturing solutions are generally more expensive to purchasethan acidic or basic denaturing solutions.

The collagen source is mixed with the denaturing solution to form acollagen source mixture. The collagen source can be allowed to swell fora period of time prior to heating. The time for which the collagensource is exposed to the denaturing solution can vary. For example, thetime could be from about 1 minute to overnight, alternatively from about2 to about 15 minutes, or alternatively about 10 minutes. When thedenaturing solution is an enzymatic solution, it is preferred tomaintain the collagen source mixture at ambient temperature or atemperature below about 55° C. for several hours or days before heatingso that the enzymes can denature the collagen before being themselvesdenatured by heating.

The amount of denaturing solution added depends on the amount ofcollagen source used. The amount of solution should be sufficient toform a fairly dilute mixture. Preferably, the ratio of milliliters ofdenaturing solution to grams of collagen source is from about 20:1 toabout 5:1, more preferably about 10:1. For example, in one embodimentabout 10 milliliters (mL) of a 0.05 N HCl solution is added for eachgram of collagen source. However, this ratio can be varied and still beeffective. For example, 50 mL of 0.05 N HCl could be added to 4.5 grams(g) of DBM. Preferably the ratio of denaturing solution to collagenstarting material is about 5:1 or higher, and/or 20:1 or lower, or 30:1or lower. However the ratio can be lower than 5:1 or higher than 30:1.In general, the more denaturing solution that is added, the longer thedrying or lyophilization process will take.

The collagen source is heated so that the collagen will be thermallydenatured to a desired extent. It has been found that heating thecollagen source mixture at 120° C. in an autoclave for 90 minutesproduced a carrier having surprisingly good physical properties, such asextrudability, moldability, irrigation resistance, cohesion in solution,and adherence to glass and metal surfaces. However, it is alsocontemplated that other times and temperatures can be sufficient toprovide a desired carrier. For example, it is contemplated that thecollagen source mixture can be heated at a temperature greater thanabout 100° C. for 180 minutes or longer, to provide a desirable carrier.In other embodiments of the present methods, it is contemplated that itmay be sufficient to heat the collagen source at a lower temperature,which in some circumstances may be sufficient to achieve the desiredextent of thermal denaturation of collagen. For example, a lowertemperature may be sufficient when the collagen source is a soft tissuesuch as a tendon, or the collagen source has been previously subjectedto other processing such as enzymatic degradation.

In various embodiments, the present methods can include heating thecollagen source to a temperature of at least about 65° C., alternativelyat least about 70° C., alternatively at least about 75° C.,alternatively at least about 80° C., alternatively at least about 85°C., alternatively at least about 90° C., alternatively at least about95° C., alternatively at least about 100° C., alternatively at leastabout 101° C., alternatively at least about 102° C., alternatively atleast about 103° C., alternatively at least about 104° C., alternativelyat least about 105° C., alternatively at least about 106° C.,alternatively at least about 107° C., alternatively at least about 108°C., alternatively at least about 109° C., alternatively at least about110° C., alternatively at least about 111° C., alternatively at leastabout 112° C., alternatively at least about 113° C., alternatively atleast about 114° C., alternatively at least about 115° C., alternativelyat least about 116° C., alternatively at least about 117° C.,alternatively at least about 118° C., alternatively at least about 119°C., alternatively at least about 120° C., alternatively at least about121° C., alternatively at least about 122° C., alternatively at leastabout 123° C., alternatively at least about 124° C., alternatively atleast about 125° C., alternatively at least about 126° C., alternativelyat least about 127° C., alternatively at least about 128° C.,alternatively at least about 129° C., alternatively at least about 130°C., alternatively at least about 131° C., alternatively at least about132° C., alternatively at least about 133° C., alternatively at leastabout 134° C., alternatively at least about 135° C. The heatingtemperature can be at most about 240° C., alternatively at most about220° C., alternatively at most about 200° C., alternatively at mostabout 180° C., alternatively at most about 160° C., alternatively atmost about 155° C., alternatively at most about 150° C., alternativelyat most about 145° C., alternatively at most about 140° C.,alternatively at most about 139° C., alternatively at most about 138°C., alternatively at most about 137° C., alternatively at most about136° C., alternatively at most about 135° C., alternatively at mostabout 134° C., alternatively at most about 133° C., alternatively atmost about 132° C., alternatively at most about 131° C., alternativelyat most about 130° C., alternatively at most about 129° C.,alternatively at most about 128° C., alternatively at most about 127°C., alternatively at most about 126° C., alternatively at most about125° C., alternatively at most about 124° C., alternatively at mostabout 123° C., alternatively at most about 122° C., alternatively atmost about 121° C., alternatively at most about 120° C. The desiredtemperature can be one or more temperatures within a range, for example,between about 105° C. and about 135° C., alternatively between about110° C. and about 125° C., or alternatively at about 120° C.Alternatively, any of the foregoing minimum temperatures or maximumtemperatures can be combined to form a range, provided the selectedmaximum is higher than the selected minimum.

In various embodiments, the present methods can include heating thecollagen source for a time of at least about 30 minutes, alternativelyat least 60 minutes, alternatively at least 75 minutes, alternatively atleast 80 minutes, alternatively at least 85 minutes, alternatively atleast about 90 minutes, alternatively at least about 95 minutes,alternatively, at least about 100 minutes, alternatively at least about105 minutes, alternatively at least about 120 minutes, alternatively atleast about 135 minutes, alternatively at least about 150 minutes,alternatively at least about 165 minutes, alternatively at least about180 minutes, alternatively at least about 195 minutes, alternatively atleast about 210 minutes, alternatively at least about 225 minutes,alternatively at least about 240 minutes. The heating time can be atmost about 72 hours, alternatively at most about 60 hours, alternativelyat most about 48 hours, alternatively at most about 36 hours,alternatively at most about 24 hours, alternatively at most about 20hours, alternatively at most about 18 hours, alternatively at most about16 hours, alternatively at most about 14 hours, alternatively at mostabout 12 hours, alternatively at most about 10 hours, alternatively atmost about 8 hours, alternatively at most about 6 hours, alternativelyat most about 4 hours, alternatively at most about 2 hours.Alternatively, any of the foregoing minimum times or maximum times canbe combined to form a range, provided the selected maximum is higherthan the selected minimum.

The heating can be done using an autoclave, a hot plate or any otherheater suitable for laboratory or industrial use. If an autoclave isused, the collagen source mixture comprising water can more readily beheated to a temperature of between about 100° C. and about 135° C.,alternatively between about 110° C. and about 130° C., or alternativelyat about 120° C. The autoclave pressure varies depending on the maximumtemperature desired. For a given autoclave configuration and dependingon the amount of collagen source mixture to be produced, the pressurewithin the autoclave unit may vary. For example, at 110° C., theautoclave pressure is at least about 8 pounds per square inch (PSI),alternatively at about 11-12 PSI at a temperature of 115° C., oralternatively at about 18 PSI while at 120° C. The heating is continuedfor a time between about 30 and about 180 minutes, alternatively betweenabout 60 and about 120 minutes, or alternatively for about 90 minutes.During this heating process, the solution may become more viscous andachieve an amber/almond color. Additionally, the volume of the acidicsolution may decrease. When a soft tissue is used as a collagen source,lower temperatures, for example between about 75° C. and about 100° C.,may be suitable.

Alternatively, another heater could be used in the denaturationprocesses described herein. For example, a hotplate or burner could beused. If a hot plate is used, the collagen source mixture can be heatedto a desired temperature, for example, between about 65° C. and about120° C., alternatively between about 80° C. and about 110° C., oralternatively at about 100° C. When the denaturing solution compriseswater, heating above 100° C. on a hot plate will generally result insome evaporation of the water. In the present methods, the heating canbe continued until the volume of the collagen source mixture decreasesby about 80%, which usually takes about 60 to about 90 minutes. Thecollagen source mixture will also become more viscous and will achievean amber/almond color.

Dissolution of the collagen source can be enhanced during heating by theuse of agitation and/or ultrasound. The dissolution can also be enhancedby use of pressure to raise the boiling point of the mixture. If theheated solution is subjected to an elevated pressure, allowing thedevelopment of elevated temperatures above 100° C., the collagen sourceis dissolved more readily.

After heating, the denatured collagen source mixture can then be allowedto cool. Cooling times can range from about 10 minutes to about 50minutes, alternatively about 20 minutes to about 40 minutes oralternatively about 25 minutes to about 35 minutes. In general, it issound practice to remove the denatured collagen source mixture from theautoclave within about 30 minutes after the conclusion of heating. Thedenaturing solution can be stirred during cooling in order to evenlydistribute any material that has not dissolved. The cooling time can bevaried and still be effective.

If the denaturing solution is acidic or basic, the denaturing solutioncan then be at least partially neutralized (rendered less acidic or lessbasic). When the denaturing solution is acidic, this can be done bytesting the pH and adding a basic solution. When the denaturing solutionis basic, an acidic solution can be added. The pH can be tested using apH monitor, pH indicator strips or any other pH measuring method.

The neutralizing acidic or basic solution to be used can be chosendepending on the particular base or acid that was used in the denaturingsolution. If hydrochloric acid was used in the denaturing solution, thensuitable basic solutions for neutralizing the acid include sodiumhydroxide (NaOH), potassium hydroxide (KOH), zinc hydroxide (Zn(OH)₂) orcalcium carbonate (CaCO₃). If hydroiodic acid was used in the denaturingsolution, then suitable bases include potassium iodide (KI) or sodiumiodide (NaI) to neutralize the acid. If sulfuric acid (H₂SO₄) was usedin the denaturing solution, then sodium hydroxide (NaOH) may bepreferred to neutralize the solution. If acetic acid (CH₃COOH) was usedin the denaturing solution, then zinc carbonate (ZnCO₃) may be preferredto neutralize the solution. If aspartic acid (HO₂CCH(NH₂)CH₂CO₂H) orlactic acid (C₃H₆O₃) was used in the denaturing solution, then calciumcarbonate (CaCO₃) may be preferred to neutralize the solution. Otheracids that can be used in the denaturing solution include stearic acid(CH₃(CH₂)₁₆COOH), fumaric acid (HO₂CCH═CHCO₂H), sorbic acid (C₆H₈O₂) andglutamic acid (C₅H₉NO₄). These acids can also be neutralized with sodiumhydroxide (NaOH).

In some embodiments, a basic solution of sodium hydroxide (NaOH) is usedto neutralize an acidic denaturing solution. Preferably the NaOHsolution has a concentration ranging from about 1 to about 10 N,alternatively from about 4 to about 6 N, alternatively about 5 N. Theamount of neutralizing base added depends on the type and molarity ofthe acid in the denaturing solution.

The neutralizing solution can be combined with water or a solutioncomprising water and some other component. For example, the othercomponent could include a component normally found in animal blood serum(e.g., sodium chloride, potassium phosphate, sodium bicarbonate, or thelike).

The neutralizing solution is added until the pH reaches a desired level,such as within about 4.0 to about 6.0, alternatively within about 4.0 toabout 4.7, or alternatively about 4.4. The amount of neutralizingsolution added can be selected based on various factors, including theamount of collagen source used, the amount of acid or base used in thedenaturing solution, the pH level of the denatured collagen sourcemixture prior to neutralization, and the length of time that thedenatured collagen source mixture cools outside of the autoclave. HClhas a relatively low vapor pressure and when it evaporates, the pH ofthe solution slowly increases. When the denaturing solution comprises0.05 N HCl, it has been observed that if the denatured collagen sourcemixture is left for about 8 hours, the pH will increase to about 4.4without the addition of a base.

The pH of the denatured collagen source mixture and osteoinductive puttycan be carefully monitored and altered. The natural condition for bloodplasma as well as synovial fluid, cerebrospinal fluid, aqueous humor(fluid within the globe of the eye) is a pH of about 7.3-7.4. However,the body has many mechanisms to maintain its biochemical balance. Theblood pH can be adjusted by several means to its normal, physiologic pH.Hence the presence of a non-physiologic material at the site of ableeding bone wound will eventually be overcome and anynon-biocompatible condition will return to normal pH. It is recognizedthat osteoinductive substances such as BMPs may be stored at slightlyacidic pH. A slightly acidic or basic pH is believed to improveprocessing as compared to a neutral or more nearly neutral pH by moreeasily maintaining the collagen source mixture in suspension or solutionthroughout processing.

The collagen source mixture after heating can be stored or furtherprocessed, such as by drying and/or freezing. For example, theneutralized mixture can then be dried. This can be done using a varietyof methods, including freeze-drying, air drying at room temperature,drying in an oven or using a heater, or other desiccation techniques.For example, the carrier can be made by evaporating the liquid presentin the collagen source mixture after heating. The liquid may beevaporated until the water content is reduced so as to provide a desiredconsistency for the carrier. If the drying is carried out underconditions wherein the denaturing solution is volatile, this may alsoallow for neutralization of an acidic or basic solution during drying.

If freeze-drying is carried out on the acidic, basic, or neutralizedsolution, the solution can be allocated into small portions, for example5 mL portions. These portions can then be exposed to a temperaturesufficient to freeze the mixture, for a time sufficient to freeze themixture. For example, an acidic solution exposed to a temperature ofabout −80 ° C. for about 30 minutes will freeze.

After freezing, a solid carrier intermediate product is provided. Thesolid carrier intermediate product can then be lyophilized to provide adry solid carrier. The solid carrier may be suitable for use as acarrier, though it may contain residual chemicals from the denaturingsolution and/or neutralizing solution. Lyophilization can be done with alyophilizing machine until the carrier is substantially free ofmoisture, as is well-known to those familiar with the technology.Lyophilization volatilizes off residual chemicals, produces a morestable intermediate for storage and handling in-process, and followspharmaceutical industry processing standards. Typically lyophilizationresults in a residual moisture content of about 10 weight percent orless, alternatively about 6 weight percent or less, alternatively about3 weight percent or less, alternatively about 2 weight percent or less,alternatively about 1 weight percent or less. After the denaturedcollagen source mixture is dried, it can be stored in a manner thatprevents air moisture from rehydrating the carrier.

Physical Properties of Carriers

The present carriers can be prepared by one or more embodiments of themethods described above, or by other methods that yield a carrier havingthe same or similar physical properties. The osteoinductive putty of thepresent disclosure comprises an osteoinductive agent and a carrier. Thecarrier can be made as described above and comprises a mixture ofcollagen fragments. For example, the carrier can include a mixture ofcollagen fragments having a substantially uniform molecular weightdistribution over a relatively wide range. In some embodiments, thecarriers have a characteristic molecular weight distribution of collagenfragments, such as the molecular weight distribution shown in FIGS. 2Athrough 2D. Alternatively or additionally, the present carriers can havea mixture of collagen fragments having an SDS-PAGE profile that does nothave a banded region within certain molecular weight ranges. Forexample, in some embodiments, the SDS-PAGE profile does not have abanded region between 29 kDa and 97 kDa, or between 39 kDa and 66 kDa,or between 45 kDa and 66 kDa. In some embodiments, the SDS-PAGE profilehas a discrete band at a location between 15 kDa and 20 kDa, and/or apartially discrete band between 20 kDa and 25 kDa. Alternatively oradditionally, the carrier can include a mixture of intact collagen,denatured collagen and denatured, hydrolyzed collagen.

By use of the phrase “does not have a banded region,” the inventorsintend to include the case where the present carriers may be measuredagainst or compared to certain properties of known materials such asporcine gelatin, Type-I collagen, unprocessed collagen, or collagenprocessed at a different time and/or temperature than that of thepresent carriers. For example, it may be observed that in someembodiments the SDS-PAGE profile includes a region which exhibits asubstantially reduced prominence of discrete, discernable, well defined,sharp, intense, narrow, or noticeable bands, banding or banded regionswhen compared to other samples including porcine gelatin, Type-Icollagen, unprocessed collagen, or collagen processed at a differenttime and/or temperature than that of the present carriers. In contrastto porcine gelatin, Type-I collagen, unprocessed collagen, or collagenprocessed at a different time and/or temperature than that of thepresent carriers, the present carriers exhibit a relatively diffuse,smoother and broader region (without prominent, intense, or discernablebands in that region) of their SDS-PAGE profiles. Such a profile isintended to be encompassed by the phrase “does not have a bandedregion”. This staining pattern indicates a region of substantially moreuniform molecular weight distribution of collagen fragments. Forexample, in some embodiments, the SDS-PAGE profile displays a relativelydiffuse and smoother region between 29 kDa and 97 kDa, or between 39 kDaand 66 kDa, or between 45 kDa and 66 kDa. In some embodiments, theSDS-PAGE profile has a relatively prominent discrete band at a locationbetween 15 kDa and 20 kDa, and/or a partially discrete band between 20kDa and 25 kDa, as compared to similarly processed stains of porcinegelatin, Type-I collagen, unprocessed collagen, or collagen processed ata different time and/or temperature than that of the present carriers.

The present carriers in wet form, such as when combined with a liquidmedium, can be in the physical form of a putty, which includes pastes,gels, viscous suspensions, solutions, liquids, and mixtures, andgenerally refers to any material that is not completely solid. Thepresent carriers have unexpectedly improved properties over previouslyused materials. Without being bound by theory, it is believed that theimproved properties of the present carriers are attributable to itsmolecular weight distributions of collagen fragments. Surprisingly themolecular weight distributions identified for the present carriersresult in the carriers having improved physical properties compared tothe properties of other materials such as gelatin. For example, thepresent carriers do not gel like gelatins and do not form hydrogels. Inthis regard, various embodiments of the present carrier are not gelatinsbut rather are entirely new materials in the form of a highly viscousliquid.

Collagen fragments are polypeptide chains having the same generalsequence and proportion of amino acids that are present in collagen.Collagen fragments can be obtained by denaturing and hydrolyzing nativecollagen, such as the fragments resulting from treating collagen asdescribed in the present methods. As another example, synthetic collagenfragments could be produced by using recombinant methods, by generatingpolypeptides of appropriate content and length.

Various embodiments of the present carriers contain a high proportion ofcollagen fragments that are smaller than the collagen fragments found intraditional gelatin. When various embodiments of the present carrierhave collagen fragments of an appropriate molecular weight distribution,it is theorized that the carrier does not form a relatively rigidlattice structure at the molecular level. Accordingly, when placed in amold at room temperature, the carrier will not maintain the shape of themold under pressure after the mold is removed. The carrier will continueto flow as a highly viscous cohesive liquid. Furthermore, reducing thecarrier's temperature below room temperature to a temperature above thefreezing point of the liquid medium does not result in a rigid, latticedstructure.

The present disclosure provides carriers that have a high hygroscopiccapacity (i.e., capacity to take up water or other solutions). Oncehydrated with an appropriate amount of water, such carriers form aviscous liquid which is highly resistant to irrigation and highlyresistant to dissolution or break up when exposed to water, blood orother solutions. The present osteoinductive putties have a highcohesiveness in solution (e.g. when submerged in or irrigated with wateror other media such as saline or blood). Various embodiments of thepresent carrier have a dissolution time of at least about 3 minutes,alternatively at least about 6 minutes. The dissolution time of variousembodiments of the present carriers and putties were determined asdescribed in Example 18. Various embodiments of the present carriershave an irrigation resistance time of at least about 5 minutes,alternatively at least about 10 minutes. The irrigation resistance timesof various embodiments of the present carriers and putties weredetermined as described in Example 19. The present carriers perform wellin surgical procedures because they tend not to swell and are not washedaway by blood or by irrigation of the surgical site. Irrigationresistance and dissolution resistance can be measured in water or inother solutions such as blood or saline. Blood is typically believed tobe a more challenging medium for irrigation resistance and fordissolution resistance.

The present disclosure provides carriers that have a creep viscositybetween about 5000 Pas and 50000 Pas, alternatively about 10826.62 Pas.The present disclosure provides carriers that have a shear rate of about0.0167 1/s. The present disclosure provides carriers that have a creeprate of about 0.00022 rad/s. The present disclosure provides carriersthat have an elastic index of about 0.5586. Procedures for determiningcreep viscosity, shear rate, creep rate, and elastic index are discussedin Example 21.

Methods of Making an Osteoinductive Putty

The present osteoinductive putties comprise an osteoinductive substanceand a carrier. The carrier comprises a mixture of collagen fragments andcan be made as described above. The osteoinductive putty can be in theform of a paste, viscous suspension or another form. The presentosteoinductive putties are shapeable, malleable, flowable, injectableand/or pourable. To form the desired osteoinductive putty, the carrier,an osteoinductive substance, and a liquid medium are combined to form acomposition having the desired consistency or properties.

The carrier can be prepared in dry form as outlined above. The carriercan be dried as also outlined above. The dry carrier can be furtherprepared for inclusion in the putty by cutting, shaping or grinding intoblocks, strips, cylinders, chips, shavings, cubes, particles, orpowders. This can be done using a variety of cutting, shaping orgrinding methods. For example, one could use hand tools, power tools, ormachine tools such as a saw, a drill, a chisel, a rotary cutting tool, amortar and pestle, a cryomill, a coffee grinder, a blender or do thegrinding by hand. The carrier can then be run through a sieve to removeany residual chunks. In some embodiments, a 850 micro sieve is used.Residual pieces of carrier can then be reground until they pass throughthe sieve.

Particle size may affect performance. Larger particle size tends toweaken particle to particle interactions within the carrier orosteogenic substance, while smaller particle size tends to strengthenthese particle to particle interactions. Particle size may be controlledin the source DBM prior to processing to form a carrier. Particle sizemay be independently controlled in the osteoinductive substance prior tomixing with the carrier to form a putty. Particle size may beindependently controlled in the ground carrier used to mix the putty.Particle size may be controlled in the mixed dry carrier andosteoinductive substance together. In some embodiments, theosteoinductive substance has a maximum particle size of less than about2 centimeters, alternatively less than about 1 centimeter, alternativelyless than about 900 microns, alternatively less than about 850 microns,alternatively less than about 600 microns, or alternatively less thanabout 400 microns. In some embodiments, the osteoinductive substance hasa minimum particle size of more than about 60 microns, alternativelymore than about 100 microns, alternatively more than about 125 microns,alternatively more than about 250 microns, alternatively more than about400 microns, alternatively more than about 600 microns, or alternativelymore than about 850 microns. In some embodiments, the dry carrier has amaximum particle size of less than about 2 centimeters, alternativelyless than about 1 centimeter, alternatively less than about 900 microns,alternatively less than about 850 microns, alternatively less than about600 microns, or alternatively less than about 400 microns. In oneembodiment, the dry carrier has a minimum particle size of more thanabout 60 microns, alternatively more than about 100 microns,alternatively more than about 125 microns, alternatively more than about250 microns, alternatively more than about 400 microns, alternativelymore than about 600 microns, or alternatively more than about 850microns. Alternatively, any of the foregoing minimum and maximum valuescan be combined to form a range, provided the selected maximum is higherthan the selected minimum.

The osteoinductive substance can be DBM, mineralized or demineralizedwhole bone, bone pieces, BMPs, growth factors or some combinationthereof. The bone that is used (either as whole bone or bone pieces, oras the source material to make one of the other osteoinductive agents)could be human or non-human bone. The bone that is used can bedemineralized (DBM) or non-demineralized bone, or a mixture thereof. Thebone that is used can be cortical bone, trabecular bone, cancellousbone, or a mixture thereof. The osteoinductive substance can be in thephysical form of bone shafts, blocks, strips, cylinders, chips,shavings, cubes, particles, or powder.

A liquid medium can be combined with the dry carrier to make a wetcarrier, and/or can be combined with the dry carrier and osteoinductivesubstance to make an osteoinductive putty. In some embodiments theliquid medium is water. Distilled, deionized, or sterilized water couldbe used. The water can be sterile water for injection or sterile salinesolution or can comprise other components, such as those normally foundin blood. Soluble calcium can be attracted to the surgical site by usinga sodium phosphate buffer. The liquid medium could alternatively be abuffered solution, such as one of the buffered solutions described inU.S. Pat. No. 6,679,918. Other liquid media for making a putty includephosphate buffered solution (PBS), low molecular weight alcohols such asethanol and butanol, high molecular weight alcohols such as decanol,diols such as glycerol, and other liquid that can participate inhydrogen bonding. A phosphate buffer will attract calcium cations to thesite from the surrounding healthy bone and create an equilibriumconcentration of the calcium at the site of healing where it is mostdesirable to grow new bone.

The liquid medium can be at room temperature. Alternatively, the liquidmedium could be heated before, during or after mixing to assist indissolution of the dry carrier in the liquid medium. For example, theliquid medium could be heated to a temperature of about 55° C. or lower,alternatively about 37° C. or lower.

It is contemplated that other active agents can optionally be added tothe carrier or implantable composition instead of or in addition to theosteoinductive substances. Other medically useful substances can beincluded in the present compositions by adding those substances to thecarrier. Such substances include collagen and insoluble collagenderivatives, hydroxyapatite and soluble solids and/or liquids dissolvedtherein, and extracellular matrices such as those from the smallintestine submucosa and urinary bladder. Other substances that can beincluded are antiviricides such as those effective against HIV andhepatitis; antimicrobial and/or antibiotics such as erythromycin,bacitracin, neomycin, penicillin, polymyxin B, tetracycline, viomycin,chloromycetin, streptomycin, cefazolin, ampicillin, azactam, tobramycin,vancomycin, clindamycin and gentamycin; antineoplastics; andanti-inflammatories such as steroids and non-steroidal anti-inflammatorydrugs (NSAIDs). It is also envisioned that one or more of the followingcan be added to the present compositions: amino acids, peptides,proteins, small interfering RNAs, vitamins, co-factors for proteinsynthesis; hormones; endocrine tissue or tissue fragments; synthesizers;enzymes such as collagenase, peptidases, oxidases; polymer cellscaffolds with parenchymal cells; angiogenic drugs and polymericcarriers containing such drugs; collagen lattices; biocompatible surfaceactive agents, antigenic agents; cytoskeletal agents; cartilagefragments; living cells such as chondrocytes, bone marrow cells,mesenchymal stem cells or multipotent adult progenitor cells (MAPCs);natural extracts; tissue transplants; bioadhesives; transforming growthfactor (TGF-beta); insulin-like growth factor (IGF-1); growth hormonessuch as somatotropin; bone digestors; antitumor agents; fibronectin;cellular attractants and attachment agents; immuno-suppressants;permeation enhancers, e.g. fatty acid esters such as laureate, myristateand stearate monoesters of polyethylene glycol, enamine derivatives,alpha-keto aldehydes.

The osteoinductive putties can include other components. For example,one or more salts or ions can be included in the putties. Saltscomprising calcium and/or phosphate can be included, such as calciumchloride, calcium sulfate, calcium phosphate, calcium hydroxyapatite,sodium phosphate, and others.

The relative amounts of carrier, osteoinductive substance, and liquidmedium used to form an osteoinductive putty or other implantablecomposition vary based on the temperature of the heating process usedduring carrier formation. Higher heat treatment process temperatures andlonger heat treatment process times generally correlate to lower waterrequirements to create a finished putty. For a carrier that wasautoclaved at 120° C., one possible mixture of DBM, carrier, and wateris 29 weight percent, 37 weight percent, and 34 weight percentrespectively. Another possible mixture of DBM carrier and water is 32weight percent, 24 weight percent, and 44 weight percent, respectively.If a temperature other than 120° C. is used when autoclaving thecarrier, then the proportions of the DBM, carrier and water need to bevaried to achieve the desired consistency. The proportions of DBM,carrier and water may also vary where other heating elements are used.

Lower water content is regarded as beneficial to allow a higherconcentration of active DBM in the putty. The present carriers andputties may be hydrated with small amounts of water and still produce aflowable, highly viscous fluid with desirable handling properties. Insome cases as little as 10%, alternatively 20%, alternatively 30%, watermay be used to hydrate an osteoinductive putty or carrier. Lowerhydration states may require more careful and complete mixing and may bemore susceptible to drying out and other effects over time with storage,handling and use. Therefore, it is desirable and beneficial in somecases to add a greater amount of water for ease of manufacture,distribution, storage, handling and use during surgery. In some cases 30weight percent, alternatively 40 weight percent, alternatively 50 weightpercent, alternatively 60 weight percent, alternatively 70 weightpercent, alternatively 80 weight percent, alternatively 90 weightpercent may be used to hydrate an osteoinductive putty or carrier.

The handling properties of the carrier or osteoinductive putty may beinfluenced by the amount of water or other fluid added for hydration.The present putties provide excellent handling characteristics,including robust consistency, strong cohesive properties, self-adhesion(the ability to stick to themselves more readily than they stick toother objects such as latex or nitrile gloves), moldability (ability toaccept and hold a formed shape), dissolution resistance (ability tomaintain shape, even when exposed to blood or water), and extrudabilityunder reasonable manual force from typical syringes or storage devices.The present putties are also remarkable in that in some embodiments theyform a viscous liquid which retains properties of self-adhesion,moldability, irrigation resistance, and dissolution resistance evenafter being extruded through a syringe or manually manipulated or formedinto shape. Alternatively, certain embodiments of the present puttiesform a viscous liquid which retains properties of self-adhesion,moldability, irrigation resistance, and dissolution resistance evenafter being extruded through a syringe, manually manipulated into aformed shape such as a ball or bead, then extruded again through asyringe one or more times.

For the temperatures discussed above, the amount of osteoinductivesubstance that is added to form the final product usually will be fromabout 5 to about 50 percent by weight, based on the total weight of thesuspension, alternatively from about 15 to about 35 percent, oralternatively from about 20 to about 29 percent. The amount of carrierthat is added to form the osteoinductive putty usually will be fromabout 5 to about 50 percent by weight, based on the total weight of thesuspension, alternatively from about 20 to about 42 percent, oralternatively from about 27 to about 38 percent. The amount of liquidmedium that is added to form the osteoinductive putty usually will befrom about 10 to about 55 percent by weight, based on the total weightof the suspension, alternatively from about 20 to about 54 percent, oralternatively from about 29 to about 53 percent.

Another advantage of the present carriers is the ability to form a puttywith a relatively small amount of liquid medium. More particularly, ithas been found that osteoinductive putties having excellent physicalproperties can be made with a relatively small amount of water. Hence,embodiments of the present osteoinductive putties can be made whichcomprise water in an amount less than about 60%, alternatively less than58%, alternatively less than 56%, alternatively less than 54%,alternatively less than 52%, alternatively less than 50%, alternativelyless than 49%, alternatively less than 48%, alternatively less than 47%,alternatively less than 46%, alternatively less than 45%, alternativelyless than 44%, alternatively less than 43%, alternatively less than 42%,alternatively less than 41%, alternatively less than 40%, alternativelyless than 39%, alternatively less than 38%, alternatively less than 37%,alternatively less than 36%, alternatively less than 35%, alternativelyless than 34%, alternatively less than 33%, alternatively less than 32%,alternatively less than 31%, alternatively less than 30%, alternativelyless than 29%, alternatively less than 28%, alternatively less than 27%,alternatively less than 26%, alternatively less than 25% of the putty orcomposition.

The carrier can be mixed with the osteoinductive substance prior toadding the liquid medium. Alternatively, the carrier can be mixed withthe liquid medium prior to adding the osteoinductive substance.Alternatively, the osteoinductive substance can be mixed with the liquidmedium prior to adding the carrier. As the carrier is added to theliquid medium, the mixture will become viscous. At some point, a viscoussuspension will be formed from the mixture of carrier, liquid medium andosteoinductive substance. More osteoinductive substance can be added orthe swelling time can be increased in order to achieve a desired levelof viscosity (e.g. paste-like or putty-like texture). Alternatively,carrier alone can be mixed with a suitable liquid medium to make anon-inductive viscous liquid carrier or manufacturing intermediatesuitable for the formation of other various finished products.

The osteoinductive putty can then be loaded into syringes or otherpackaging for storage and use. Preferably the packaging is well suitedfor use in a medical and/or clinical environment. For example it can bedurable, flexible and easy to handle. The packaging can also be barrierresistant to chemicals, grease, moisture, viruses and bacteria. Thepackage could be sterile. In preferred embodiments the package issealed, for example, it is sealed so that it is moisture resistant. Asanother example, a hermetically sealed package is sealed in an airtightmanner. Examples of suitable materials for packaging and sealing theputty include thermoplastic films, polyester films, polyethylene fibers,para-aramid fibers and combinations thereof. For surgical applicationsthe packaging could be a double pouch. The double pouch could be made upof an inner package and an outer package. The inner package can be madeof a polyester film, such as Mylar®, and a polyethylene film, such asTyvek® (both available from DuPont). The outer package can be made of amoisture resistant foil bag made of aluminum and transparent plasticwith a Tyvek® Header pouch.

In embodiments where syringes are used, the syringes can be stored insuch a manner as to keep them sterile. For example they can beirradiated and stored in vacuum packed bags. The moisture barrierproperties of the syringe or package can have an impact on the stabilityand other properties of the osteoinductive putty. If the putty in placedin a package that has some degree of permeability to water, the puttymay gain or lose moisture (water content), which may affectextrudability, cohesiveness and other properties.

Accordingly, another aspect of the present disclosure is a kitcomprising the osteoinductive putty disposed in a suitable package, suchas a syringe or a dual chamber package. In some embodiments, theosteoinductive putty is hermetically sealed in the package.

In certain embodiments where a syringe is used, the syringe barrel,plunger tip, plunger, or cap may each be made of polypropylene,polycarbonate, silicone, neoprene, santoprene, or any other suitableengineered thermoplastic or other resin commonly used in the medicaldevice industry. In some embodiments, the package comprises a syringehaving an opening at a first end and a plunger at a second end, whereinthe putty is disposed inside the syringe, a removable cap attached tothe opening of the syringe so as to form a seal. In some embodiments ofthe present kits, the putty can be extruded from a typical medicalproduct delivery device or package such as a polypropylene syringe bypressure on the plunger of about 15 to 150 Newtons or higher. The typeand configuration of the syringe may influence the specific forcerequired to extrude a given putty.

The pH of the final putty can be in the range of about 4 to about 8,alternatively from about 4 to about 7. The pH of the final putty can betested using a flat surface electrode if desired. If water was used asthe liquid medium, the pH will be from about 4.0 to about 4.7.

Methods of Using an Osteoinductive Putty

Bone defects are generally viewed as being an imperfection or void in abone tissue, which is of sufficient physical dimensions as to not healspontaneously within a desired time period. Bone defects can includefractures, cracks, and osteosarcomas (bone cancer lesions), amongothers. Bone compositions in the form of putties, gels or pastes areutilized clinically to aid or improve healing of the osseous defect.

Bone compositions are also used to correct surgical bone defects thatcan be caused by trauma, pathological disease, surgical intervention orother situations where defects need to be managed in osseous surgery.Bone compositions are also commonly used to augment healing in thetreatment of a broad range of musculoskeletal disorders. Bonecompositions have been effective in reconstruction or replacement ofbone defects, to augment fracture repair, to strengthen arthrodeses andto fill defects after treatment of tumors.

Those familiar with the technology will recognize the many orthopedicapplications of the osteoinductive putties of this disclosure. However,by way of illustration rather than limitation, for purposes ofarthrodesis of the spine, one mode of using this composition would be atan early stage of vertebral disk degeneration or subsequent to trauma.Diagnosis of trauma or degeneration is followed by formation of a smallorifice, or a plurality of small orifices in the intervertebralcartilage at the site of degeneration. The osteoinductive putty is theninjected into the intervertebral space to aid in inducing arthrodesis. Asimilar procedure could be used with other joints or bone damage.

The osteoinductive putties of this disclosure can be applied to a bonedefect in a variety of ways. It is desirable to have the bone defectfiller in the form of a stable, viscous putty or paste to facilitate theplacement of the bone growth medium into the surgical site which isusually uneven in shape and depth. The surgeon can then pack thecomposition into the bone defect. The surgeon can take the putty on aspatula or other instrument and trowel it into the site. The surgeon canalso use his/her fingers to shape the osteoinductive putty into theproper configuration to fit the site being corrected. The presentosteoinductive putty is particularly advantageous for implantation byhand because there is little loss of material when handled by latexgloves.

The osteoinductive putty can be placed into a syringe or other packagefor easy storage and application. Preferably, the osteoinductive puttyis placed into the syringe or package soon after the liquid medium isadded to the other materials, since exposure to open air may result inmoisture loss over time. It may be desirable to have the packages readyfor loading before the liquid medium is combined with the othermaterials. In order to ensure that the putty has the desirableconsistency, a small portion of the putty is placed into the rear of thesyringe. The plunger is then inserted into the rear of the syringe andplaced in an upright position with the ejection end of the syringeputting downwards. A reasonable manual force (such as between about 50and about 300 Newtons) is then applied to the plunger. If the putty inthe syringe is extruded, the putty has the desired density and physicalproperties. The syringes can be irradiated and stored for later use. Thesyringe or other package can be hermetically sealed to prevent or reducethe loss of moisture from the putty or loss of sterility. Sealing thepackage using moisture resistant packaging allows for extended storageof the putty in a ready to use form. Such packaging allows for the puttyto remain in a hydrated form. The syringes can be sealed in a clear foilpouch, and the syringes and pouches can be sterilized, such as by lowdose gamma irradiation.

The surgeon can later inject the osteoinductive putty into the affectedarea of the bone. This is done by injecting the syringe into the area ofthe bone defect and applying pressure to the plunger. Sufficientpressure is supplied to the plunger to eject the desired amount ofosteoinductive putty. The amount of osteoinductive putty desired and therequired force will vary depending on the size and shape of the affectedarea of the bone. The putty can be further manipulated after ejectionfrom the syringe either by hand or with a spatula or other instrument.

In some embodiments, the osteoinductive putty components (the carrierand osteoinductive substance) and means for applying the osteoinductiveputty (for example, syringe or spatula) can be provided in a unitarykit. In other embodiments, the osteoinductive substance and the carriercan be prepared under sterile conditions and stored separately, or mixedand stored together, for later use. To facilitate clinical usage of thepresent putties, carriers, and compositions, the osteoinductivesubstance and the carrier can be packaged separately and combined at thetime of usage. In other embodiments, the components can be combined toproduce an osteoinductive putty or other implantable composition, whichis then packaged, in a premixed formulation.

A premixed osteoinductive putty provides the advantage of requiring verylittle preparation by the individual clinician at the time of usage. Insome embodiments, the osteoinductive putty can be stored in animplantation device, such as a syringe, which will be used to apply thecomposition to a bone defect site. The osteoinductive putty can, forexample, be stored in a 1 to 10 cc syringe (such as a 1 cc, 3 cc, or 5cc syringe) that is capable of being coupled to a large gauge deliverytube/needle of appropriate length and inside diameter. In this regard, adelivery tube with an inside diameter of not less than 13 gauge isappropriate for the injection delivery into an implant site.

For on-site preparation, the carrier and osteoinductive substance can beprovided in freeze-dried aliquots that are mixed and rehydrated justprior to being combined for use in clinical applications, in someembodiments. On-site preparation has the advantage of increasing theability to vary the concentrations and quantities of the carrier andosteoinductive substance used in preparation of the osteoinductiveputty. Furthermore, on-site preparation permits the addition of optionalcomponents at the discretion of the clinician.

Physical Properties of Osteoinductive Putty

The osteoinductive putty of the present disclosure comprises anosteoinductive substance and a carrier. The carrier can be made asdescribed above and comprises a mixture of collagen fragments. Forexample, the carrier can include a mixture of collagen fragments havinga substantially uniform molecular weight distribution over a relativelywide range. As other examples, the mixture of collagen fragments canhave an SDS-PAGE profile that does not have a banded region withincertain molecular weight ranges. As another example, the carrier caninclude a mixture of intact Type I collagen, denatured Type I collagenand denatured, hydrolyzed Type I collagen. It has been found that theparticular mixture of collagen fragments can have a significant effecton physical properties (such as extrudibility, moldability, solubility,cohesivity, and others), and the present disclosure identifies carriershaving novel mixtures of collagen fragments, which results in carriershaving excellent physical properties.

Bloom strength is a measure of gel strength. As discussed in Example 20,some embodiments of the present osteoinductive putties do not have ameasurable Bloom strength, because they fail to trigger the initial 4 gprobe resistance force required to measure Bloom strength.

The present osteoinductive putties also have excellent physicalproperties and are generally superior to many previously used materials.For example, various embodiments of the osteoinductive putties areresistant to irrigation. In some embodiments, the putties are formulatedwith relative amounts of carrier, osteoinductive substance, and liquidmedium such that the putties do not wash away under the pressure of asurgical lavage (about 150 mm Hg). As another example, the putties arenot carried away by body fluids at the surgical site. As yet anotherexample of their physical properties, various embodiments of theosteoinductive putties can adhere to metals, which can be useful to themanufacturer of the putty as well as to clinician. This can beparticularly useful when attempting to apply the bone graft at aninterface between bone and a metal implant. Various embodiments of theosteoinductive putties do not leave a substantial residue on latex ornitrile gloves, and can be manipulated without easily falling apart in awet environment such as a surgical site. The present putties can behandled and shaped by a surgeon to form a desired shape or fit a desiredsurgical site.

Various embodiments of the present osteoinductive putties are highlyresistant to taking up water or other solutions and are resistant toirrigation. The present osteoinductive putties have a high cohesivenessin solution (e.g. water or other media such as saline), making them lesslikely to leave the site of implantation. The high cohesiveness insolution is demonstrated by a high cohesion time in solution.Specifically, the present osteoinductive putties have a cohesion time ofabout 3 minutes or longer, or alternatively of about 6 minutes orlonger, and/or an irrigation resistance time of about 5 minutes orlonger or alternatively of about 10 minutes or longer. This allows theosteoinductive putties to be irrigated or completely submerged in asolution and subsequently handled without loss of physical properties.

The present osteoinductive putties also have excellent extrusionproperties. The present osteoinductive putties retain good moldabilityand cohesiveness after extrusion. This allows for desirable surgicalperformance, in that the putty can be molded to fit a surgical sitefollowing extrusion from a syringe or other delivery device. The presentosteoinductive putties exhibit consistent and reliable extrusion of asmooth continuous or semi-continuous bead of putty, with a reasonableextrusion force even following exposure to air. The putties can beextruded, such as in use of a syringe, with a moderate manual force (forexample, about 2 to about 200 Newtons). Surprisingly, after the puttyhas been extruded, the putty can be loaded back into a syringe andextruded again without showing a loss of cohesiveness, such as crumblingor shredding. The putties can be extruded at least two, three or fourtimes without exhibiting substantial loss of cohesiveness. In someembodiments and with some syringe configurations the putties may havehigher extrusion force requirements (for example, about 50 to about 500Newtons).

The present disclosure provides osteoinductive putties that have a creepviscosity between about 11000 Pas and about 48000 Pas, alternativelyabout 38428.102 Pas. The present disclosure provides carriers that havea shear rate of about 0.0047 l/s. The present disclosure providescarriers that have a creep rate of about 0.00006 rad/s. The presentdisclosure provides carriers that have an elastic index of about 0.531.Procedures for determining creep viscosity, shear rate, creep rate, andelastic index are discussed in Example 21.

Methods for Making a Formed Implant

In some embodiments, an implantable composition suitable for making, orfor use as, a formed implant is made by subjecting a collagen source toa denaturation process at a suitable temperature for a suitable time.Formed implants may form a hydrogel, or partial hydrogel through atleast some of their volume under various conditions of temperature andhydration. Formed implants are therefore not necessarily extrudable ormoldable following extended storage to the same extent as osteoinductiveputties. The present disclosure, however, provides formed implants witha controlled degree of hydrogel formation and with retention of someviscous liquid properties, and which remain extrudable, moldable,resistant to irrigation and/or resistant to dissolution (cohesion insolution), and retain their osteoinductive properties, even followingextrusion, forming, molding or shaping, and after terminal sterilizationand extended storage (for example, sterilization by gamma irradiationfollowed by storage overnight or longer, or for at least one, two orthree months, or up to six months or one year) in a sealed package.

It has been found that heating the collagen source mixture at 120° C. inan autoclave for 60 minutes produced an implantable composition havingsurprisingly good physical properties suitable for a formed implant,such as handling, irrigation resistance and cohesion in solution. It hasalso been found that heating a collagen source mixture at about 100° C.for a time between about 90 and 180 minutes produced an implantablecomposition having surprisingly good physical properties suitable for aformed implant. Various embodiments of these implantable compositionsand formed implants are not extrudable and they do not flow, and theyform or comprise gels. These embodiments are shapeable, rubbery and/ormalleable. Various embodiments of the present formed implants are highlycohesive in water and resistant to irrigation, making them less likelyto leave the site of implantation. This allows the resulting formedimplants to be irrigated or completely submerged in a saline solutionand subsequently handled without loss of physical properties. The highwater resistance also ensures that the formed implant is not carriedaway by body fluids at the surgical site.

Formed implants may encompass shapes such as a ball, rod, capsule,pellet, oval, egg, sphere, sheet, film or membrane. Such formed implantsmay be extruded, rolled, compressed, stretched, pulled or otherwisemanipulated by a machine or simple mechanical device, or created byhand, either intraoperatively or preoperatively and at the surgery site,at the recovery site, or at a discrete processing location or facility.

As an example of a denaturation process for making an implantablecomposition suitable for use in a formed implant, a collagen source,such as demineralized bone matrix, is exposed to a denaturing solution.The DBM is then heated so that the collagen will be thermally denatured.The heating can be done using an autoclave or other heater as describedabove. The collagen source can heated be at 120° C. for 60 minutes, orat about 100° C. for a time between about 90 and 180 minutes. Afterheating, the denatured collagen source mixture is then allowed to cool.If the denaturing solution is acidic or base, the denaturing solutioncan then be neutralized as described above. The implantable compositioncan then be dried and/or frozen. The present implantable compositionscan be the product of the foregoing denaturation process, or of othermethods that yield an implantable composition having the same or similarphysical properties. Alternatively or additionally, the implantablecomposition comprises a mixture of collagen fragments having an SDS-PAGEprofile substantially the same as shown in Lane I of any of FIGS. 2Athrough 2D.

The formed implant or implantable composition can further include anosteoinductive substance, and a liquid medium. Other agents andsubstances, such as an osteogenic substance or other medically usefulsubstance, can be included.

The following examples further illustrate the present invention butshould not be construed as limiting its scope in any way.

EXAMPLE 1

This example demonstrates a novel method of making a carrier for use inan implantable composition, such as an osteoinductive putty. 67 g of DBMwas added to 670 mL of a denaturing solution. In this example, thedenaturing solution was a very dilute aqueous solution of hydrochloricacid (e.g., 0.05 N). Then the mixture was placed in an autoclave andheld at 120° C. for 90 minutes. After autoclaving, the denaturedcollagen source mixture was allowed to cool for 15 to 30 minutes, andthen was mixed by hand using a spoonula. The pH of the mixture was thentested using pH strips and brought to a pH within the range of 4.0 to6.0 using an appropriate volume of an aqueous NaOH solution (5 N). Themixture was then pipetted into Petri dishes and frozen at −80 ° C. forat least 30 minutes. The frozen mixture was then lyophilized, and thePetri dishes were covered in parafilm and stored at room temperatureuntil the dry carrier was to be used for preparing an implantablecomposition.

EXAMPLE 2

This example demonstrates a novel method of making a carrier for use inan implantable composition, such as an osteoinductive putty. 67 g of DBMis added to 670 mL of a denaturing solution. In this example, thedenaturing solution is a dilute aqueous solution of sodium hydroxide(e.g. 0.05 N). Then the mixture is placed in an autoclave and held at120° C. for 90 minutes. After autoclaving, the denatured collagen sourcemixture is allowed to cool for 15 to 30 minutes, and then is mixed byhand using a spoonula. The pH of the mixture is then tested using pHstrips and brought to a pH within the range of 4.0 to 6.0 using anappropriate volume of an aqueous HCl solution (5 N). The mixture is thenpipetted into Petri dishes and frozen at −80 ° C. for at least 30minutes. The frozen mixture is then lyophilized, and the Petri dishesare covered in parafilm and stored at room temperature until the drycarrier is to be used for preparing an implantable composition.

EXAMPLE 3

This example demonstrates a novel method of making a carrier for use inan implantable composition, such as an osteoinductive putty. 10 g of DBMis added to 100 mL of a denaturing solution. In this example, thedenaturing solution is a very dilute aqueous solution of hydrochloricacid (e.g., 0.05 N). Then the mixture is placed on a heater (such as ahot plate) and brought to a boil, between 60 and 100° C. The mixture isboiled for 180 minutes or until the volume of liquid is reduced by 80%.After boiling, the mixture is allowed to cool for 15-30 minutes, then ismixed by hand using a spoonula. The pH of the mixture is then testedusing pH strips and brought to a pH within the range of 4.0 to 6.0 usingan appropriate volume of an aqueous basic solution, such as 5 N NaOH.The mixture is then pipetted into Petri dishes and frozen at −80 ° C.for at least 30 minutes. The frozen mixture is then lyophilized, and thePetri dishes are covered in parafilm and stored at room temperatureuntil the dry carrier is to be used for preparing an implantablecomposition.

EXAMPLE 4

This example demonstrates a novel method of making a carrier for animplantable composition, such as an osteoinductive putty, from acollagen source other than DBM. In this example, the collagen source isa section or entire piece of sterilized human cortical bone that has notbeen demineralized. The bone is added to a denaturing solution such as0.05 N HCl. The volume of denaturing solution in mL should be 10 timesthe bone's weight in grams. The denaturing solution and bone form acollagen source mixture, which is heated using an autoclave as detailedin Examples 1 and 2. Since the bone is mineralized, a higher temperatureis used for thermal denaturation, such as a temperature of 140° C. orhigher. After heating, the mixture is allowed to cool for 15-30 minutes,then is mixed by hand. The mixture can be subjected to grinding eitherbefore or after denaturing to reduce the particle size of any residualbone. The pH of the mixture is then tested and brought to a pH withinthe range of 4.0 to 6.0 using an appropriate volume of a neutralizingsolution, such as an aqueous basic solution (5 N NaOH). The mixture isthen pipetted into Petri dishes and frozen at −80 ° C. for at least 30minutes. The frozen mixture is then lyophilized, and the Petri dishesare covered in parafilm and stored at room temperature until the drycarrier is to be used for preparing an implantable composition.

EXAMPLE 5

This example demonstrates a novel method of making a xenogenic carrierfor an implantable composition, such as an osteoinductive putty. Thexenogenic carrier is made from an animal collagen source, such as aporcine, ovine or bovine collagen source. It is contemplated that thehigh temperatures used for thermal denaturation of the collagen sourcewill also reduce the immunogenicity of the xenogenic carrier. 67 g ofbovine, ovine, or porcine demineralized bone matrix (DBM) is added to670 mL of 0.05 N HCl or another denaturing solution. The mixture iseither heated using an autoclave as detailed in Examples 1 and 2 orusing other heaters as detailed in Example 3. After heating, thecollagen source mixture is allowed to cool for 15-30 minutes, and thenis mixed by hand using a spoonula. The pH of the mixture is then testedusing pH strips and brought to a pH within the range of 4.0 to 6.0 usingan appropriate volume of a neutralizing solution, such as 5 N NaOH. Themixture is then pipetted into Petri dishes and frozen at −80 ° C. for atleast 30 minutes. The frozen mixture is then lyophilized, and the Petridishes are covered in parafilm and stored at room temperature until thedry carrier is to be used for preparing an implantable composition.

EXAMPLE 6

This example demonstrates a novel method of making a xenogenic carrierfor use in an implantable composition, such as an osteoinductive putty,from a collagen source other than DBM. In this example, the collagensource is a section or entire piece of sterilized bovine, ovine, orporcine cortical bone that has not been demineralized. The bone is addedto a denaturing solution such as 0.05 N HCl. The volume of denaturingsolution in mL should be 10 times the bone's weight in grams. Thedenaturing solution and bone form a collagen source mixture, which isheated using an autoclave as detailed in Examples 1 and 2. Since thebone is mineralized, a higher temperature is used for thermaldenaturation, such as a temperature of 140° C. or higher. After heating,the denatured collagen source mixture is allowed to cool for 15-30minutes, then is mixed by hand. The pH of the mixture is then testedusing pH strips and brought to a pH within the range of 4.0 to 6.0 usingan appropriate volume of neutralizing solution, such as 5 N NaOH. Themixture is then pipetted into Petri dishes and frozen at −80 ° C. for atleast 30 minutes. The frozen mixture is then lyophilized, and the Petridishes are covered in parafilm and stored at room temperature until thedry carrier is to be used for preparing an implantable composition.

EXAMPLE 7

This example demonstrates a novel method of making a carrier forproducing an osteoinductive putty. In this example, a soft tissue isused as the collagen source. A human tendon is selected for use as astarting material in this example. The tendon is ground and lyophilizedto form a powder. A denaturing solution, such as 0.05 N HCl, is added tothe tendon powder such that the volume of denaturing solution in mL isten times the tendon powder's weight in grams. This collagen sourcemixture is either heated using an autoclave as detailed in Examples 1-2or using other heaters as detailed in Example 3. When a soft tissue isused as the collagen source, it is contemplated that lower temperatures,such as about 75° C. or about 100° C. may be suitable. After heating,the mixture is allowed to cool for 15-30 minutes, then is mixed by hand.The pH of the mixture then tested using pH strips and brought to a pHwithin the range of 4.0 to 6.0 using an appropriate volume ofneutralizing solution, such as 5 N NaOH. The mixture is then pipettedinto Petri dishes and frozen at −80 ° C. for at least 30 minutes. Thefrozen mixture is then lyophilized, and the Petri dishes are covered inparafilm and stored at room temperature until the dry carrier is readyto be used for preparing an implantable composition.

EXAMPLE 8

This example demonstrates a novel method of making an osteoinductiveputty. This process begins with a carrier produced according to Examples1-7. The carrier is ground to a fine powder using a blender. The groundmaterial is then sieved through an 850 micron sieve to remove anyresidual non-powdered chunks of carrier. Residual pieces of carriercakes are then re-ground until they pass through the sieve.

To prepare the putty, the dry powdered carrier is first mixed with asuitable amount of an osteoinductive substance (dry DBM). Then asuitable amount of room temperature sterile distilled deionized water(ddH₂O) is added to form a putty. If a temperature of 120° C. was usedwhen autoclaving the carrier, a mixture of DBM, carrier, and water is29% (by weight), 37% (by weight), and 34% (by weight) respectively.

The putty can then be loaded into a syringe for use. The pH of the finalputty can be tested by using a flat surface electrode if desired (see,e.g. U.S. Pat. No. 6,679,918). The pH should be about 4.0 to about 6.0.

EXAMPLE 9

A series of putties are made according to the process of Example 8 andhaving a variety of consistencies. Table 1 shows the amounts (in grams)of carrier, osteoinductive substance, and water (in mL) combined to makethe putties.

TABLE 1 Formulations for Osteoinductive Putties Total (% by weight)(grams) Powder Water Total % % % yield Sample Carrier DBM (g) (mL) (g)DBM carrier water cc 9A 0.35 0.27 0.62 0.7 1.32 20 27 53 1.00 9B 1.751.35 3.10 3.5 6.60 20 27 53 5.00 9C 3.5 2.7 6.20 7 13.20 20 27 53 10.009D 0.35 0.27 0.62 0.6 1.22 22 29 49 0.92 9E 1.75 1.35 3.10 3 6.10 22 2929 4.62 9F 3.5 2.7 6.20 6 12.20 22 29 49 9.24 9G 0.35 0.27 0.62 0.5 1.1224 31 45 0.85 9H 1.75 1.35 3.10 2.5 5.60 24 31 45 4.24 9I 3.5 2.7 6.20 511.20 24 31 45 8.48 9J 0.35 0.27 0.62 0.4 1.02 26 34 39 0.77 9K 1.751.35 3.10 2 5.10 26 34 39 3.86 9L 3.5 2.7 6.20 4 10.20 26 34 39 7.73 9M0.35 0.27 0.62 0.35 0.97 28 36 36 0.73 9N 1.75 1.35 3.10 1.75 4.85 28 3636 3.67 9O 3.5 2.7 6.20 3.5 9.70 28 36 36 7.35 9P 0.35 0.27 0.62 0.30.92 29 38 33 0.70 9Q 1.75 1.35 3.10 1.5 4.60 29 38 33 3.48 9R 3.5 2.76.20 3 9.20 29 38 33 6.97

EXAMPLE 10

In this example, the extrudability of an embodiment of the presentosteoinductive putty is compared to a putty comprising porcine gelatinas a carrier. An embodiment of the present osteoinductive putty wasprepared according to Example 8. Another composition was prepared bycombining 4.23 g of DBM, 2.67 g of porcine gelatin, and 14 mL water.Both samples were extruded through a Beckton Dickinson 5 mL slip tipsyringe reference number 301603. Although the porcine gelatincomposition was extrudable if used as recommended, such as within 20minutes, it was not extrudable following wet storage for a longer periodof time. When the porcine gelatin based composition was left overnight,it was not extrudable through the syringe.

EXAMPLE 11

This example demonstrates a novel method of making osteoinductiveputties. A carrier produced according to one of Examples 1-7 isprovided. The carrier is ground to a fine powder using a blender. Theground material is then sieved through an 850 micron sieve to remove anyresidual non-powdered chunks of carrier. Residual pieces of carriercakes are then re-ground until they pass through the sieve without beingforced.

To prepare the putty, the powdered dry carrier is first mixed with asuitable amount of dry DBM. Then a suitable amount of sterile distilleddeionized water (ddH₂O) at 90 ° C. is added to form a putty. If atemperature of 120° C. was used when autoclaving the carrier, a mixturecomprises 29% (by weight) DBM, 37% (by weight) carrier, and 34% (byweight) water.

The putty can then be loaded into a syringe for use. The pH of the finalputty can be tested, such as by using a flat surface electrode. The pHcan be between about 4.0 and about 6.0.

EXAMPLE 12

This example demonstrates a novel method of making an osteoinductiveputty. A carrier produced according to one of Examples 1-7 is provided.The carrier is ground to a fine powder using a blender. The groundmaterial is then sieved through an 850 micron sieve to remove anyresidual non-powdered chunks of carrier. Residual pieces of carriercakes are then re-ground until they pass through the sieve.

To prepare the putty, the dry powdered carrier is first mixed with asuitable amount of whole bone. Then a suitable amount of roomtemperature sterile distilled deionized water (ddH₂O) is added to form aputty. If a temperature of 120° C. was used when autoclaving thecarrier, a mixture of whole bone, carrier, and water is 29% (by weight),37% (by weight), and 34% (by weight) respectively.

The putty can then be loaded into a syringe for use. The pH of the finalputty can be tested, such as by using a flat surface electrode. The pHcan be between about 4.0 and about 6.0.

EXAMPLE 13

This example demonstrates a novel method of making an osteoinductiveputty. This process begins with the carrier produced according toExamples 1-7. The carrier is ground to a fine powder using a blender.The ground material is then sieved through an 850 micron sieve to removeany residual non-powdered chunks of carrier. Residual pieces of carriercakes are then re-ground until they pass through the sieve.

To prepare the putty, the dry powdered carrier is first mixed with asuitable amount of a combination of BMPs and growth factors. Then asuitable amount of room temperature sterile distilled deionized water(ddH₂O) is added to form a putty. If a temperature of 120 ° C. was usedwhen autoclaving the carrier, a mixture of the combined BMPs and growthfactors, the carrier, and water is 29% (by weight), 37% (by weight), and34% (by weight) respectively.

The putty can then be loaded into a syringe for use. The pH of the finalputty can be tested, such as by using a flat surface electrode. The pHcan be between about 4.0 and 6.0.

EXAMPLE 14

FIGS. 1A through 1C are photographs of putties that have been extrudedfrom a syringe. The different putties comprise carriers prepared fromdemineralized bone matrix at different temperatures. Each of the puttieswas made with 5.18 g of carrier, 4.0 g of DBM, and 4.71 mL of sterilizeddistilled deionized water, resulting in a putty that was about 37%carrier, about 29% DBM, and about 34% water. FIG. 1A shows a puttycontaining a carrier made by heating a collagen source mixturecomprising a 1:10 (g:mL) ratio of DBM and 0.05 N HCl in an autoclave ata temperature of 120° C. for 90 minutes. The putty comprised 5.18 gcarrier, 4.0 g DBM and 4.71 mL ddH2O. This putty exhibited excellentextrudability from the syringe, and it retained good moldability andcohesiveness after extrusion. FIG. 1B shows a putty containing a carriermade by heating a collagen source mixture comprising a 1:10 ratio of DBMand 0.05 N HCl in an autoclave at a temperature of 100° C. for 90minutes. The putty comprised 5.18 g carrier, 4.0 g DBM and 4.71 mLddH2O. This putty was crumbly and had poor consistency and cohesiveness,and it did not extrude easily. FIG. 1C shows a putty containing acarrier made by heating a collagen source mixture comprising a 1:10ratio of DBM and 0.05 N HCl in an autoclave at a temperature of 55° C.for 90 minutes. This putty was also crumbly and had poor consistency andcohesiveness, and it did not extrude easily. For this example, BecktonDickinson 5 mL slip tip syringes reference number 301603 were modifiedby cutting off the nozzle, leaving a wider opening at the end oppositethe plunger. The syringes were modified in this manner because the puttyshown in FIGS. 1B and 1C could not be extruded through the normalsyringe.

EXAMPLE 15

In this example, a variety of samples were analyzed to determine whetherthere were differences between the present carriers and other materials,such as gelatins and collagen sources processed under differentprocedures. The present example shows differences in the molecularweight distributions and SDS-PAGE profiles of the collagen fragments inthe present carriers compared to other materials. In this example,Sample A was a putty made from 5.18 g of carrier, 4.0 g of active DBM,and 4.71 mL of water. The carrier was made by mixing a 1:10 (g:mL) ratioof DBM and 0.05 N HCl, and heating the mixture at 120° C. in anautoclave for 90 minutes. Sample B was a putty made from 5.18 g ofcarrier, 4.0 g of active DBM, and 4.71 mL of water. The carrier was madeby mixing a 1:10 ratio of DBM and 0.05 N HCl, and heating the mixture at55° C. in an autoclave for 90 minutes. Sample C was a wet carrier madefrom 9.18 g of carrier and 4.71 mL of water. The carrier was made bymixing a 1:10 ratio of DBM and 0.05 N HCl, and heating the mixture at120° C. in an autoclave for 90 minutes. Sample D was a wet carrier madefrom 9.18 g of carrier and 4.71 mL of water. The carrier was made bymixing a 1:10 ratio (g:mL) of DBM and 0.05 N HCl, and heating themixture at 55° C. in an autoclave for 90 minutes. Sample E was a puttymade from 2.67 g of carrier, 4.23 g of active DBM, and 14 mL of water.The carrier was a commercially available fine porcine gelatin carrier.Sample F was a putty made from 2.67 g of carrier, 4.23 g of active DBM,and 14 mL of water. The carrier was a commercially available coarseporcine gelatin carrier. Sample G was a wet carrier made from 6.9 g ofcarrier and 14 mL of water. The carrier was a commercially availablefine porcine gelatin carrier. Sample H was a putty made from 5.18 g ofcarrier, 4.0 g of active DBM, and 4.71 mL of water. The carrier was madeby mixing a 1:10 ratio of DBM and 0.05 N HCl, and heating the mixture at100° C. in an autoclave for 90 minutes. Sample I was a wet carrier madefrom 9.18 g of carrier and 4.71 mL of water. The carrier was made bymixing a 1:10 ratio of DBM and 0.05 N HCl, and heating the mixture at100° C. in an autoclave for 90 minutes.

The molecular weight distribution of any of the foregoing carriers isanalyzed by SDS-PAGE (Western Blot). FIGS. 2A through 2H set forthSDS-PAGE profiles (shown by Western blot analyses) of the productsresulting from various treatments of collagen sources. The experimentswere carried out as follows: One mL of 0.1N acetic acid was added to 1.5mL Eppendorf tubes that contain approximately 50 mg of sample. Theliquid in tubes was first mixed using 1 mL pipette and then mixedvigorously for 30 seconds using a vortexer (concentration wasapproximately 50 mg/mL including insoluble material). One hundredmicroliters (or approximately 1/10 amount for sample that was solid) ofthe sample in the tube was transferred to a new Eppendorf tube and anadditional 900 microliter of 0.1N acetic acid was added (approximately 5mg/mL including insoluble material). Tubes were then vortexed again for30 seconds. Two hundred microliters of solution (contains insolublepellet) were transferred to a new 1.5 mL Eppendorf tube and 100microliters of three times (3×) concentrated SDS-PAGE sample buffer(final concentration was 1× after mixing with two volume of the sample)without 2-mercaptoethanol (2-ME). Concentration of sample wasapproximately 3.34 mg/mL, however, the amount of insoluble material atthe end was not determined. All samples had some amount of precipitateat the end. Tubes were vortexed for 30 seconds and boiled for 3 min inwater bath. Tubes were then microcentrifuged at 12,000 rpm for 1 min toremove large aggregate. Supernatant was used for SDS-PAGE. Gels were 12lanes 8-16% gradient pre-made gels for Mini protean II gelelectrophoresis set from Bio-rad.

Type I collagen (1 mg/mL) from Rockland Immunochemicals, Inc. was usedas a control. This was in 0.1N acetic acid and no precipitate was seenin the tube. Two hundred microliter of the Type I collagen was mixedwith 100 microliter of 3× sample buffer like other samples. Thus, finalconcentration of the control Type I collagen was 0.67 mg/mL.

20 microliter of each sample was loaded onto wells of SDS-PAGE. Amountof control Type I collagen in the lane (20 microliter) is 13.4 microgram(0.67 microgram/microliter×20). Amount of other samples in each lane is68 microgram (0.34 microgram/microliter×20 microliter), however, actualamount of proteins is not known since all samples had insoluble materialat the end of preparation of samples for SDS-PAGE.

SDS-PAGE was performed at constant voltage (100 V) for 2.5 h usingBio-rad Mini Protean II electrophoresis set. Proteins in the gels weretransferred to nitrocellulose filter using a standard semi-dry proteintransfer system (Bio-rad) for 45 min at constant voltage (15 V). Aftertransfer, nitrocellulose filter was stained with 0.1% ponceau red toconfirm protein transfer and mark the position of molecular weightmarkers.

Western blotting Nitrocellulose filters were blocked in 0.5% bovineserum albumin (BSA) in NET/NP40 (150 mM NaCl, 2 mM EDTA, 50 mM Tris-HClpH 7.5, 0.3% NP40) for 30 min at 22° C. Filters were then incubated withrabbit anti-Type I collagen antibodies (Rockland Immunochemicals, Inc,1:4,000 dilution, total volume 40 mL of 0.5% BSA NET/NP40) for 45 min at22° C. in a plastic box on a shaker. Filters were washed three timesusing ˜40 mL of NET/NP40, 5 min each on a shaker. Filters were thenincubated with horse-radish peroxidase-conjugated goat anti-rabbit IgGantibodies (Southern Biotechnology, 1:7,000 dilution, total volume of 40mL in 0.5% BSA NET/NP40) for 45 min at 22° C. in a plastic box on ashaker. Filters were washed three times using ˜40 mL of NET/NP40, 5 mineach on a shaker, then washed twice using ˜40 mL of phosphate bufferedsaline. Filters were then placed on a clean sheet of plastic wrap afterremoving extra liquid using paper towel. Four mL/filter of developer(Pierce, Supersignal Westpico) was overlayed on a filter and incubatedfor 5 min in a dark. Filters were placed between clear folder afterremoving extra liquid. Images were obtained by exposing x-ray films(Kodak, BioMax MR) to nitrocellulose filters in a clear folder for 10seconds to 4 min. FIGS. 2A through 2H show films at various exposuretimes. Films were developed after exposure. X-ray films were scanned anddata were organized using Photoshop 7.0 and Canvas 9.01 software. Noadjustment of contrast, brightness, or other parameters was performedfor the figures.

Samples C, D, F and I were selected for further analysis. Thecharacteristic of sample C was quite different from other samples when0.1N acetic acid was added to dried powder in the tubes. When 1 mL of0.1N acetic acid was added to ˜50mg of dried powder, sample C was highlysoluble with very small amount (approximately 5% in volume) ofprecipitates. Sample D was mostly insoluble with ˜80% volume ofinsoluble precipitates. Sample F appeared to absorb liquid and formed asolid gel. Sample I was soluble but formed very thick liquid. After theinitial ponceau red staining, sample C was diluted 1:5, sample D wasused as it was, and samples F and I were diluted 1:10 to normalize theamount of proteins per lane. Based on this the amount of protein is asfollows: C,14 microgram; D, 68 microgram; F and I, 7 microgram. Thesevalues are approximate.

As can be seen from these results, the main differences of Type Icollagen (I-C) in sample C compared with others when analyzed bySDS-PAGE and Western blotting appeared to be 1) lack of distinct bands,2) predominance of low molecular weight (smaller than 200kD) I-C, and 3)presence of very low molecular weight (smaller than 20kD and 25kD) I-C.The I-C in sample C shows diffuse distribution without forming distinctbands like all other samples. There are some differences in size anddistribution of bands between samples, however, all samples exceptsample C has 20-30 distinct bands whereas sample C shows diffuselydistributed I-C. Also, it appears that more than 90% of I-C in sample Cis smaller than 200kD, in striking contrast to other samples. Lastly,presence of very low molecular weight (smaller than 20kD and 25kD) I-Cis seen almost exclusively in sample C.

As discussed above, the phrase “does not have a banded region,” isintended to include the case where the present carriers may be measuredagainst or compared to certain properties of known materials such asporcine gelatin, Type-I collagen, unprocessed collagen, or collagenprocessed at a different time and/or temperature than that of thepresent carriers. For example, it may be observed that the SDS-PAGEprofile for Sample C includes a region which exhibits a substantiallyreduced prominence of discrete, discernable, well defined, sharp,intense, narrow, or noticeable bands, banding or banded regions whencompared to the other samples. In contrast to the other samples, thepresent carriers exhibit a relatively diffuse, smoother and broaderregion (without prominent, intense, or discernable bands in that region)of their SDS-PAGE profiles. Such a profile is intended to be encompassedby the phrase “does not have a banded region”.

FIG. 2A shows the Western blot without 2-mercaptoethanol as a reducingagent. FIG. 2B shows the Western blot of the same samples with2-mercaptoethanol as a reducing agent. FIG. 2C shows the Western blotfrom an exposure time of 10 seconds. FIG. 2D shows the Western blot froman exposure time of 20 seconds. FIG. 2E shows the Western blot from anexposure time of 30 seconds. FIG. 2F shows the Western blot from anexposure time of one minute. FIG. 2G shows the Western blot from anexposure time of two minutes. FIG. 2H shows the Western blot from anexposure time of four minutes.

FIGS. 2A through 2D show that the carrier of Sample C had asubstantially uniform molecular weight distribution within the range offrom about 45 kDa to about 66 kDa and within other ranges, includingfrom about 29 kDa to about 97 kDa, from about 29 kDa to about 66 kDa,from about 45 kDa to about 97 kDa. Sample C also has a sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE) profile, and itsSDS-PAGE profile did not have a banded region between about 45 kDa andabout 66 kDa, or a banded region between about 29 kDa and about 97 kDa.The SDS-PAGE profile of Sample C did include a discrete band betweenabout 15 kDa and about 20 kDa, whereas the SDS-PAGE profiles of theother samples did not include a discrete band in that region.

As discussed above, the phrase “does not have a banded region,” isintended to include the case where the present carriers may be measuredagainst or compared to certain properties of known materials such asporcine gelatin, Type-I collagen, unprocessed collagen, or collagenprocessed at a different time and/or temperature than that of thepresent carriers. For example, it may be observed that the SDS-PAGEprofile for Sample C displays a relatively diffuse and smoother regionbetween 29 kDa and 97 kDa or between 45 kDa and 66 kDa when compared tothe other samples. As another example, it may be observed that theSDS-PAGE profile for Sample C has a relatively prominent discrete bandat a location between 15 kDa and 20 kDa, as compared to the othersamples.

EXAMPLE 16

In this example, a variety of samples were analyzed to determine whetherthere were differences between the present carriers and other materials,such as gelatins and collagen sources processed under differentprocedures. The present example shows differences in the HPLCchromatograms of the collagen fragments in the present carriers comparedto other materials. The test was carried out as follows: 1 mg ofcollagen was suspended in 1mL Tris-HCl buffer (0.1 mol/L, pH 7.8,containing 0.1 mol/L NaCl) and denatured at 60° C. for 3 hours. 500 uLof this sample was added to a new tube then 100 uL of a freshly made 0.1mg/mL tyrosine solution was added. The samples were then heated at 37°C. for an additional 4 hours. The samples were then filtered using apolytetraflorsethylene (PTFE) syringeless filter and injected for HighPerformance Liquid Chromatography (HPLC) analysis. HPLC was run using anAgilent 1100 series binary pump, a Phenomenex Synergi 4u Hydro-RP 80A(2×150 mm; 4 um; S/N=106273-5) plus C18 guard column (2 mm×4 mm), amanual Rheodyne 7125, 25 uL injection loop, and an Agilent 1100 G1314AUV/Vis detector. The mobile phase A component is 0.2% Acetic acid inH2O. The mobile phase B component is 0.2% Acetic acid inacetonitrile/The gradient at 0.15 mL/min isA:B(min)=100:0(0-5)=>5:95(50-65)=>100:0(75-95). The injection volume is20 mL. The wavelength is 220 nm.

FIGS. 3A through 3F set forth HPLC analyses of the products resultingfrom various treatments of collagen sources. Sample 3A was a wet carriermade from 6.9 g of commercially available food quality Knox gelatin and14 mL of water. Sample 3B was a wet carrier made from 6.9 g of carrierand 14 mL of water. The carrier was a commercially available fineporcine gelatin carrier. Sample 3C was a putty made from 5.18 g ofcarrier, 4.0 g of active DBM, and 4.71 mL of water. The carrier was madeby mixing carrier DBM and 0.05 N HCl in a 1:10 ratio (g:mL), and heatingthe mixture at 55° C. in an autoclave for 90 minutes. Sample 3D was awet carrier made from 6.9 g of carrier and 14 mL of water. The carrierwas a commercially available course porcine gelatin carrier. Sample 3Ewas a putty made from 5.18 g of carrier, 4.0 g of active DBM, and 4.71mL of water. The carrier was made by mixing carrier DBM and 0.05 N HClin a 1:10 ratio (g:mL), and heating the mixture at 120° C. in anautoclave for 90 minutes. Sample 3F was a putty made from 5.18 g ofcarrier, 4.0 g of active DBM, and 4.71 mL of water. The carrier was madeby mixing carrier DBM and 0.05 N HCl in a 1:10 ratio (g:mL), and heatingthe mixture at 100° C. in an autoclave for 90 minutes.

FIG. 3A is the HPLC profile of a commercially available food qualityKNOX® gelatin sample. FIG. 3B is the HPLC profile of a fine porcinegelatin sample. FIG. 3C is the HPLC profile of DBM processed at 55° C.and mixed with DBM particles. FIG. 3D is the HPLC profile of a coarseporcine gelatin sample. FIG. 3E is the HPLC profile of DBM processed at120° C. FIG. 3F is the HPLC profile of DBM processed at 100° C. As canbe seen from these results, the gelatin samples had a characteristicdouble peak which is not present in FIG. 3E. This is consistent withthis sample comprising a carrier that is not a gelatin.

EXAMPLE 17

In this example, the extrudability of a variety of carrier and puttysamples were analyzed to determine whether there were differences in howthe samples performed upon extrusion from a syringe. The test wascarried out as follows: A total of 47 samples of carrier, putty, orgelatin were mixed, packed into syringes and sealed in bags for storage.All carrier and active DBM was selected from a store of pooled (multipledonor) DBM.

Samples 17A, 17A2, and 17A3 were putties made from 5.18 g of carrier,4.0 g of active DBM, and 4.71 mL of water. The carriers were made inbatches by mixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL,and heating the mixture at 120° C. in an autoclave for 90 minutes.Sample 17A4 was a putty made from 5.19 g of carrier, 4.0 g of activeDBM, and 6.22 mL of water. The carrier was made in batches by mixing 1part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 120° C. in an autoclave for 90 minutes.

Sample 17B was a putty made from 5.18 g of carrier, 4.0 g of active DBM,and 4.71 mL of water. The carrier was made in batches by mixing 1 partcarrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating the mixtureat 55° C. in an autoclave for 90 minutes. Sample 17BX was a putty madefrom 5.18 g of carrier, 4.0 g of active DBM, and 8.71 mL of water. Thecarrier was made in batches by mixing 1 part carrier DBM in mg to 10parts 0.05 N HCl in mL, and heating the mixture at 55° C. in anautoclave for 90 minutes.

Samples 17C and 17C2 were wet carriers made from 9.18 g of carrier and4.71 mL of water. The carriers were made in batches by mixing 1 partcarrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating the mixtureat 120° C. in an autoclave for 90 minutes.

Sample 17D was a wet carrier made from 9.18 g of carrier and 4.71 mL ofwater. The carrier was made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 55° C. in anautoclave for 90 minutes. Sample 17DX was a putty made from 5.18 g ofcarrier, 4.0 g of active DBM, and 5.71 mL of water. The carrier was madein batches by mixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl inmL, and heating the mixture at 55° C. in an autoclave for 90 minutes.

Samples 17E and 17E2 were putties made from 2.67 g of carrier, 4.23 g ofactive DBM, and 14 mL of water. The carriers were a commerciallyavailable fine porcine gelatin carrier. Samples 17F and 17N were puttiesmade from 2.67 g of carrier, 4.23 g of active DBM, and 14 mL of water.The carriers were a commercially available coarse porcine gelatincarrier. Samples 17G and 17G2 were wet carriers made from 6.9 g ofcarrier and 14 mL of water. The carriers were a commercially availablefine porcine gelatin carrier.

Samples 17H and 17H2 were putties made from 5.18 g of carrier, 4.0 g ofactive DBM, and 4.71 mL of water. The carriers were made in batches bymixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, andheating the mixture at 100° C. in an autoclave for 90 minutes. Sample17HX was a putty made from 5.18 g of carrier, 4.0 g of active DBM, and6.71 mL of water. The carrier was made in batches by mixing 1 partcarrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating the mixtureat 100° C. in an autoclave for 90 minutes.

Samples 171 and 171X were wet carriers made from 9.18 g of carrier and4.71 mL of water. The carriers were made in batches by mixing 1 partcarrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating the mixtureat 100° C. in an autoclave for 90 minutes. Samples 1713 and 1714 wereputties made from 5.19 g of carrier, 4.0 g of active DBM, and 6.22 mL ofwater. The carriers were made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 100° C. inan autoclave for 90 minutes.

Sample 17J was a wet carrier made from 9.18 g of carrier and 4.71 mL ofwater. The carrier was made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 100° C. inan autoclave for 180 minutes.

Samples 17K and 17KX were wet carriers made from 9.18 g of carrier and4.71 mL of water. The carriers were made in batches by mixing 1 partcarrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating the mixtureat 120° C. in an autoclave for 60 minutes.

Samples 17L and 17LX were putties made from 5.18 g of carrier, 4.0 g ofactive DBM, and 4.71 mL of water. The carriers were made in batches bymixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, andheating the mixture at 100° C. in an autoclave for 180 minutes.

Samples 17M and 17MX1 were putties made from 5.18 g of carrier, 4.0 g ofactive DBM, and 4.71 mL of water. The carriers were made in batches bymixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, andheating the mixture at 120° C. in an autoclave for 60 minutes. Sample17MX2 was a putty made from 5.18 g of carrier, 4.0 g of active DBM, andgreater than 4.71 mL of water. The carrier was made in batches by mixing1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 120° C. in an autoclave for 60 minutes.

Samples 170 and 1702 were putties made from 5.18 g of carrier, 4.0 g ofactive DBM, and 20.71 mL of water. The carriers were made in batches bymixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, andheating the mixture at 100° C. in an autoclave for 90 minutes.

Sample 17P was a putty made from 5.18 g of carrier, 4.0 g of active DBM,and 20.71 mL of water. The carrier was made in batches by mixing 1 partcarrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating the mixtureat 120° C. in an autoclave for 60 minutes.

Sample 17C2X was a wet carrier made from 9.18 g of carrier and 5.71 mLof water. The carrier was made in batches by mixing 1 part carrier DBMin mg to 10 parts 0.05 N HCl in mL, and heating the mixture at 120° C.in an autoclave for 90 minutes.

Sample 17Q2 and 17R2 were putties made from 5.18 g of carrier, 4.0 g ofactive DBM, and 20.71 mL of water. The carriers were made in batches bymixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, andheating the mixture at 120° C. in an autoclave for 75 minutes.

Sample 17S3 was a putty made from 5.18 g of carrier, 4.0 g of activeDBM, and 4.71 mL of water. The carrier was made in batches by mixing 1part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 135° C. in an autoclave for 90 minutes. Sample 17S4 was aputty made from 5.19 g of carrier, 4.0 g of active DBM, and 6.22 mL ofwater. The carrier was made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 135° C. inan autoclave for 90 minutes.

Sample 17T3 was a putty made from 5.18 g of carrier, 4.0 g of activeDBM, and 4.71 mL of water. The carrier was made in batches by mixing 1part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 135° C. in an autoclave for 75 minutes.

Sample 17U3 was a putty made from 5.18 g of carrier, 4.0 g of activeDBM, and 4.71 mL of water. The carrier was made in batches by mixing 1part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 120° C. in an autoclave for 180 minutes.

Sample 17V3 was a putty made from 5.18 g of carrier, 4.0 g of activeDBM, and 4.71 mL of water. The carrier was made in batches by mixing 1part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 115° C. in an autoclave for 90 minutes. Sample 17V3X was aputty made from 5.18 g of carrier, 4.0 g of active DBM, and 7.07 mL ofwater. The carrier was made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 115° C. inan autoclave for 90 minutes.

Sample 17W3 was a putty made from 5.18 g of carrier, 4.0 g of activeDBM, and 4.71 mL of water. The carrier was made in batches by mixing 1part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 118° C. in an autoclave for 90 minutes. Sample 17W3X was aputty made from 5.18 g of carrier, 4.0 g of active DBM, and 7.07 mL ofwater. The carrier was made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 118° C. inan autoclave for 90 minutes.

Sample 17X4 was a putty made from 5.19 g of carrier, 4.0 g of activeDBM, and 6.22 mL of water. The carrier was made in batches by mixing 1part carrier DBM in mg to 10 parts 0.05 N HCl in mL, and heating themixture at 110° C. in an autoclave for 90 minutes.

Where the material in a given sample was noted to be especially stiff ordry, extra samples were mixed with additional water (as indicated inTable 2) and stored either in a Becton Dickinson 5 mL slip tip syringe(reference number 301603), having a nominal 12 millimeter bore insidediameter, nominal 2 millimeter extrusion tip inside diameter and nominal9 millimeter extrusion tip length plus a nominal 3 millimeter slopedfunnel or transition zone between the bore and the extrusion tip, orplaced directly in a poly bag, as noted. Samples 17A, 17B, 17BX, 17C,17D, 17DX, 17E, 17F, 17G, 17H, 17HX, 171, 171X, 17J, 17K, 17KX, 17L,17LX, 17M, 17MX1 17MX2, 17N, 170, and 17P were then stored for 48-72hours. After these samples were prepared, it was recognized that theBeckton Dickinson 5 mL slip tip syringes are not as moisture resistantas might be desirable. Accordingly, Samples 17A2, 17C2, 17C2X, 17E2,17G2, 17H2, 170X, 17Q2, and 17R2 were prepared and stored for only 1-3hours in the same Becton Dickinson 5mL slip tip syringes. Additionalputty or carrier material from some samples were prepared fornon-extruded handling and moldability testing, this additional materialwas loaded into a custom Oratech 5 mL storage device, featuring anominal 10 millimeter bore inside diameter, nominal 10 millimeterextrusion tip inside diameter, with only a minor step or lip between theinside bore diameter and the inside tip diameter (to prevent over travelof the plunger). This storage device features an ejection plunger and anairtight silicone cap covering the free end. This storage time wasestimated to be long enough to allow any potential gelatinous setup tooccur, but short enough to avoid excessive moisture loss.

After these samples were tested, alternative processing conditionswithin a defined range of times at various temperatures were tested andthe carrier or putty was evaluated. Accordingly, samples 17A3, 17S3,17T3, 17U3, 17V3, 17V3X, 17W3, and 17W3X and 1713 were prepared andstored for 1-3 hours, again in the same Beckton Dickinson 5 mL slip tipsyringes. After these samples were tested, a spectum of puttyperformance was explored across varying processing temperatures for agiven processing time (and also across varying processing times for agiven temperature). It was also recognized that the Becton Dickinsonsyringes might be the limiting factor in extrusion force testing, due totheir deformation under extrusion loads, their small tip size and largebore size (low extrusion area to bore area ratio). It was furtherrecognized that alternative ratios of dry carrier, DBM, and water mightbe used to produce a carrier or putty of the present invention.Accordingly, samples 17A4, 1714, 17S4 and 17X4 were prepared using ahigher concentration of water, and then stored for 1-3 hours in Oratechsyringes (Oratech/Ultradent; South Jordan, Utah; part number 3310),having a 10 millimeter nominal bore inside diameter and a 2.5 millimeternominal extrusion tip inside diameter, and nominal 7 millimeterextrusion tip length with a flat barrel end, showing no noticeablefunnel or transition region between the bore and the extrusion tip. TheOratech syringes were selected due to their lower deformation underextrusion loads, their larger tip inside diameter, smaller bore insidediameter (higher extrusion area to bore area ratio), more rigidmechanical construction, and their twist-on locking cap feature.

After the storage time, the bags were opened and the syringes containingthe samples were retrieved for testing. Each syringe was mounted in acylindrical collett and supported in a test fixture on an Instron forcetesting machine (Loadcell model # 2525805, Serial # UK1178; Frame 5865Series; System Serial # 001167, System ID # 5865P4532). The Instron loadcell was centered atop the syringe plunger and brought into contact toan initial load of about 0.01 kN. A test profile was then executed,commanding a downward motion of 10mm over a period of 10 seconds. At theconclusion of the test profile, the load cell released to an idle loadof about 0.01 kN, before repeating the profile for a second time,releasing the load cell again, then repeating the profile for a thirdtime. For each syringe, three motions of 10 mm each were attemptedunless syringe failure occurred prior to the third motion. Such syringefailure is referred to as No Extrusion, and is indicated as “NE” inTable 2. Maximum reaction force was observed from the computer controlscreen for each 10 mm motion, and force-deflection data was logged to anoutput file at each motion. The presence or absence of any putty behindthe plunger tip was noted as “blow-by” on the data sheet. Color andphysical condition of the syringe and extrudate was also recorded foreach syringe tested. Where there was no extrusion after all threemotions, this was also noted as “No Extrusion” (NE).

Results are shown in Table 2 below. As can be seen from these results,the putties made by heating DBM at a temperature of 120° C. for 90minutes had better extrudability, as indicated by consistent andreliable extrusion of a smooth continuous or semi-continuous bead ofputty, with a reasonable extrusion force, even following overnightstorage in an uncapped syringe. Further testing of samples 17A4, 1714,17S4, and 17X4 with the Oratech syringes demonstrated a clear decreasingtrend in extrusion force with increasing processing temperature for agiven processing time and putty composition. Extrusion force data is notavailable for samples 17A3, 17S3, 17T3, 17U3, 17V3, 17V3X, 17W3, and17W3X and 1713 because the data did not appear to be reliable.

EXAMPLE 18

In this example, the cohesion in solution (“dissolution time”) of avariety of carrier and putty samples were analyzed to determine whetherthere were differences in cohesiveness. The test was carried out asfollows: The samples from Example 17 were formed into a bead ofapproximately 1 millimeter in diameter and approximately 10 to 20millimeters in length. Where the material in a given sample was noted tobe especially stiff or dry, extra samples were mixed with the same ormore water and stored either in a syringe or directly in a poly bag, asnoted. After the storage time, the bags were opened and syringesretrieved for testing. The extrudate from Example 17, above, was usedwhen available. For those samples where the syringe failed prior toproducing any extrudate, material was taken from the extra, baggedmaterial or other storage device produced at syringe filling. The sample(approximately 10 to 20 millimeter length of extrudate, or roughlyequivalent amount of bagged/non-extruded material) was placed into abeaker of water at 37° C. with visual observation ofcohesion/dissolution over time as recorded with a manual stopwatch.Dissolution was considered to have occurred when the sample visibly lostshape and fell apart, either spontaneously, or with occasionally mildagitation after 1 minute in the water. Results are shown in Table 2below. As can be seen from these results, the putties made by heatingDBM at a temperature of 120° C. for 90 minutes had higher cohesiveness,as indicated by higher dissolution times of 3:00 minutes (sample A) and6:00 minutes (sample C). Samples 17KX and 17IX also exhibited gooddissolution times of 5:00 minutes each. For samples 17A3, 17S3, 17T3,17U3, 17V3, 17V3X, 17W3, and 17W3X, extrudate or excess material wasrolled by hand into a ball prior to testing, and dissolution times above2 minutes were not recorded, as indicated by a “+” sign in the table.For samples 17A4, 1714, 17S4 and 17X4, dissolution times were nottested.

EXAMPLE 19

In this example, the “irrigation resistance time” of a variety ofcarrier and putty samples were analyzed to determine whether there weredifferences in resistance to irrigation. The test was carried out asfollows: The samples from Example 17 were formed into a bead ofapproximately 1 millimeter in diameter and approximately 10 to 20millimeters in length. Where the material in a given sample was noted tobe especially stiff or dry, extra samples were mixed with the same ormore water and stored either in a syringe or directly in a poly bag, asnoted. After the storage time, the bags were opened and syringesretrieved for testing. The extrudate from Example 17, above, was usedwhen available. For those samples where the syringe failed prior toproducing any extrudate, material was taken from the extra, baggedmaterial produced at syringe filling. The sample (approximately 10 to 20millimeters length of extrudate, or roughly equivalent amount ofbagged/non-extruded material) was placed on a glass microscope slide,applying light to moderate finger pressure to promote adherence of thesample to the slide while maintaining the basic shape of the samplewhere possible. Results are shown in Table 2 below. Where the sample didnot stick to the microscope slide it was noted as “did not stick” (DNS).As can be seen from these results, the putties made by heating DBM at atemperature of 120° C. for 90 minutes had better irrigation resistance,as indicated by higher irrigation resistance times of 4 minutes and 55seconds (sample A) and more than 10 minutes (sample C). For samples17A3, 17S3, 17T3, 17U3, 17V3, 17V3X, 17W3, and 17W3X, irrigation timesabove 5 minutes were not recorded, as indicated by a “+” sign in thetable. For samples 17A4, 1714, 17S4 and 17X4, irrigation times were nottested.

TABLE 2 Extru- Disso- Syringe sion lution Irr. Blow Load Time Time #Sample Description DBM Observations By Moldable (N) (m · ss) (m · ss)17A DBM, water and carrier made x golden brown/honey color y 400 3.00 4.55 at 120° C. for 90 minutes paste in syringe; light tan, smoothstrong-semi- continuous bead; 2nd syringe ears yielded 17B DBM, waterand carrier made x v. light tan dense paste in n NE 0.00  0.00 at 55° C.for 90 minutes syringe; no extrusion (NE); extra sample bag tested fordiss/irr 17BX DBM, water and carrier made off-white-tan spongy paste inn N/A 0.00  0.04 at 55° C. for 90 minutes with syr; fluffy white brokenbeads additional 4 mL water extr 17C Carrier made at 120° C. at 90 darkbrown/honey color paste y 480 6.00 10+ minutes in syringe; med tan,smooth strong-fully-continuous bead; IRR test stopped at 10 minutes,still holding strong 17D Carrier made at 55° C. at 90 v. light tan densepaste in n 550 NE n/a n/a minutes syringe; no extr.; 17DX DBM, water andcarrier made x v. light tan dense paste in n 500 NE 0.10  0.05 at 55° C.for 90 minutes with syringe; no extr.; extra sample additional 1 mLwater bag w/dense spongy crumbs tested for diss/irr 17E DBM, water andfine porcine x blotch/mottled off-whie & n 160 0.01  0.05 gelatincarrier yellow stiff spongy paste in syr; rough, open-cell, highlybroken tubes extr. 17F Water and coarse porcine translucent whitew/yellow y 380 0.03  0.01 gelatin carrier cast lumpy looking paste insyr; clear/white granules/beads extruded 17G Water and fine porcinegelatin translucent off-white-yellow y 410 0.08 DNS carrierslightly-lumpy looking paste in syr; fluffy-white granules extruded 17HDBM, water and carrier made x mottled light/med tan paste in n 270; 590n/a n/a at 100° C. for 90 minutes syr; no extr 17HX DBM, water andcarrier made x extra bag w/mottled n/a n/a 1.00  0.00 at 100° C. for 90minutes with light/med tan clumpy additional 2 mL water and granules; noextr extrabag 17I Water and carrier made at golden brown/honey color n500 NE n/a n/a 100° C. for 90 minutes paste in syringe; no extr. 17IXwater and carrier made at extra bag w/mottled golden n/a n/a 5.00 DNS100° C. for 90 minutes, and brown/honey colored rubbery extrabag spongyclumps; no extr; large clump used for irr test, still together at 5 minbut starting to flake apart 17J water and carrier made at goldenbrown/honey color y 520 0.30 DNS 100° C. for 180 minutes paste insyringe; light tan, rough strong-semi-continuous bead 17K water andcarrier made at golden brown/honey color n 550 NE n/a n/a 120° C. for 60minutes paste in syringe; no extr. 17KX water and carrier made at extrabag w/mottled golden n/a n/a 5.00 DNS 120° C. for 60 minutes-extrabagbrown/honey colored rubbery spongy clumps; no extr; large clump used forirr test, still together at 5 min but starting to flake apart 17L DBM,water and carrier made x golden brown/honey color n 550 NE n/a n/a at100° C. for 180 minutes paste in syringe; no extr. 17LX DBM, water andcarrier made x extra bag w/mottled n/a n/a 0.45 DNS at 100° C. for 180minutes- light/med tan spongy extrabag granules; no extr 17M DBM, waterand carrier made x slightly mottled golden n 550 NE n/a n/a at 120° C.for 60 minutes brown/honey color paste in syringe; no extr. 17MX1 DBM,water and carrier made x extra bag w/mottled n/a n/a 0.30 DNS at 120° C.for 60 minutes- light/med tan spongy extrabag granules; no extr 17MX2DBM, water and carrier made x v. light tan dense paste in y 420 0.08 0.00 at 120° C. for 60 minutes, with syringe; off-white-tan-yellowunknown volume of additional discontinuous bead extr.; water 17N DBM,water and coarse porcine x off-white-yellow mottled n 190 0.00  0.00gelatin carrier paste in syr; fluffy white small spongy granules extr;IRR sample left some sticky residual on glass 17O DBM, water and carriermade x off-white-tan dense paste in n  60 0.05  0.01 at 100° C. for 90minutes with syringe; off-white-tan-yellow additional 16 mL watersemi-smooth highly discontinuous bead extr.; 17P DBM, water and carriermade x med tan dense paste in n 310 0.06  0.00 at 120° C. for 60 minuteswith syringe; v. light tan smooth additional 16 mL water discontinuousbead extr.; 17A2 DBM, water and carrier made x med/light tan paste insyringe; y excellent 293 2.30 12:00+ at 120° C. for 90 minutes smoothsolid continuous extruded bead. mixed 13:30, tested 16:00 = 2:30 setuptime 17C2 Carrier made at 120° C. for 90 dark tan/honey color with yyes, but 470 2.30  0.30 minutes lumpy bead sticky 17C2X Carrier made at120° C. for 90 dark tan/honey color with y too sticky 226 3.00  0.30minutes with additional 1 mL rough lumpy bead to mold water well 17Q2DBM, water and carrier made x light tan color with smooth n yes 339 3.00 0.05 at 120° C. for 75 minutes with solid continuous bead additional 16mL water 17R2 DBM, water and carrier made light/med tan with lumpy nyes, 278 3.00  0.03 at 120° C. for 75 minutes with irregular continuousbead clumpy, additional 16 mL water sticky 17H2 DBM, water and carriermade x blotchy/mottled off-white & n yes, 371 0.08  0.02 at 100° C. for90 minutes yellow stiff spongy paste in spongy, syr; rough, open-cell,highly crumbly broken tubes extr. 17O2 DBM, water and carrier madesmooth yellow paste makes n yes, spongy  55 0.06  0.02 at 100° C. for 90minutes with puffy semi-continuous bead additional 16 mL water 17E2 DBM,water and fine porcine x off-white paste makes puffy n yes, but 164 0.08 0.00 gelatin carrier semi-continuous bead crumbly 17G2 Fine porcinegelatin carrier light-off-white paste makes y no, too 370 0.10  0.00very puffy, very irregular crumbly continuous bead mixed 15:30, tested16:50 = ~1:20 setup time 17A3 DBM, water, and carrier made x y good datanot 2.00+  5.00+ at 12°0C. for 90 minutes available 17S3 DBM, water, andcarrier made x Didn't extrude. y good data not 0.30  5.00+ at 135° C.for 90 minutes available 17T3 DBM, water, and carrier made x n Good, butdata not 2.00+  5.00+ at 135° C. for 75 minutes tacky available 17U3DBM, water, and carrier made x syringe failed during 3^(rd) etxr. y good.data not 2.00+  5.00+ at 120° C. for 180 minutes available 17V3 DBM,water, and carrier made x syringe failure. n hard to data not 2.00+ DNSat 115° C. for minutes mold, not available tacky 17V3X DBM, water, andcarrier made x n Fluffy, .data not 1.00  0.05 at 115° C. for 90 minutescrumbly, available @ 150% H2O hard to mold, not tacky 17W3 DBM, water,and carrier made x Didn't extrude. n yes data not 2.00 DNS at 118° C.for 90 minutes available 17W3X DBM, water, and carrier made x n Fluffybut data not 1.00  0.10 at 118° C. for 90 minutes moldable available @150% H20 with effort 17I3 DBM, water, and carrier made x No extrusion. nno, like gel data not 2.00+ DNS at 100° C. for 90 minutes (NEG availableCONTROL) 17A4 DBM, water, and carrier made x n yes 119 not not at 120°C. for 90 minutes + tested tested NEW H2O CONC. 17I4 DBM, water, andcarrier made x lighter in color than 17A4 n No, 593 not not at 100° C.for 90 minutes + crumbly tested tested NEW H2O CONC. and fluffy 17S4DBM, water, and carrier made x darker shade than17A4 n Very well  25 notnot at 135° C. for 90 minutes + tested tested NEW H2O CONC. 17X4 DBM,water, and carrier made x lighter in color than 17A4 n Somewhat, 368 notnot at 110° C. for 90 minutes + with a lot tested tested NEW H2O CONC.of effort, although fluffy and crumbles

EXAMPLE 20

In this example, the Bloom strength of a variety of carrier and puttysamples were analyzed to determine whether there were differences inBloom strength. The test was carried out as follows: Sample 20A was aputty made from 5.18 g of carrier, 4.0 g of active DBM, and 4.71 mL ofwater. The carrier was made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 120° C. inan autoclave for 90 minutes. Sample 20B was a putty made from 5.18 g ofcarrier, 4.0 g of active DBM, and 4.71 mL of water. The carrier was madein batches by mixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl inmL, and heating the mixture at 55° C. in an autoclave for 90 minutes.Sample 20C was a wet carrier made from 9.18 g of carrier and 4.71 mL ofwater. The carrier was made in batches by mixing 1 part carrier DBM inmg to 10 parts 0.05 N HCl in mL, and heating the mixture at 120° C. inan autoclave for 90 minutes. Sample 20D was a wet carrier made from 9.18g of carrier and 4.71 mL of water. The carrier was made in batches bymixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, andheating the mixture at 55° C. in an autoclave for 90 minutes. Sample 20Ewas a putty made from 2.67 g of carrier, 4.23 g of active DBM, and 14 mLof water. The carrier was a commercially available fine porcine gelatincarrier. Sample 20F was a putty made from 2.67 g of carrier, 4.23 g ofactive DBM, and 14 mL of water. The carrier was a commercially availablecoarse porcine gelatin carrier. Sample 20G was a wet carrier made from6.9 g of carrier and 14 mL of water. The carrier was a commerciallyavailable fine porcine gelatin carrier. Sample 20H was a putty made from5.18 g of carrier, 4.0 g of active DBM, and 4.71 mL of water. Thecarrier was made in batches by mixing 1 part carrier DBM in mg to 10parts 0.05 N HCl in mL, and heating the mixture at 100° C. in anautoclave for 90 minutes. Sample 201 was a wet carrier made from 9.18 gof carrier and 4.71 mL of water. The carrier was made in batches bymixing 1 part carrier DBM in mg to 10 parts 0.05 N HCl in mL, andheating the mixture at 100° C. in an autoclave for 90 minutes.

Dry material was weighed into water to create a 6.67% solution instandard Bloom bottles with stoppers. The mix was then stirred and leftto hydrate for approximately 3 hours at room temperature. Once soaked,bottles were placed in a 65° C. bath for 20 minutes, stirringoccasionally to assure that the composition was completely dissolved.After allowing the Bloom jars to cool for 15 minutes at roomtemperature, they were then conditioned for 16 hours in a 10° C. waterbath. The Bloom jar was centered with the probe just above the samplesurface. The probe is a 12.7 mm diameter flat face, cylindrical probewith a sharp edge. The test begins when the designated 4 g trigger forceis reached. The probe then penetrates the gelatin to a target depth of 4mm at a speed of 0.5 mm/s, and then retracts. The peak force is acceptedas the gel strength in grams Bloom, uncorrected for moisture.

Results are shown in Table 3 below. As can be seen from these results,the putty and carrier made by heating DBM at a temperature of 120° C.for 90 minutes (samples 20A and 20C) did not have a measurable Bloomstrength, since they failed to trigger the initial 4 g force requiredfor the Bloom measurement. The Bloom strength of samples 20B and 20Dalso could not be measured. These samples were a clear liquid withconsiderable solids settled at the bottom after stirring. In samples 20Aand 20C, only a small amount of solids settled after stirring.

TABLE 3 Sample No. Bloom Strength 20A Not measurable 20B Not measurable20C Not measurable 20D Not measurable 20E  65 g Bloom 20F 276 g Bloom20G 144 g Bloom

Samples 20A, 20B, 20C and 20 D did not form a gel. Samples 20E formed asoft gel and Samples 20 F and 20 G formed clear gels.

EXAMPLE 21

In this example, the dynamic viscosities of a variety of carrier andputty samples were analyzed to determine whether there were differencesin dynamic viscosity. In this example, Sample 21A was a putty made from5.18 g of carrier, 4.0 g of active DBM, and 4.71 mL of water. Thecarrier was made by mixing a 1:10 (g:mL) ratio of DBM and 0.05 N HCl,and heating the mixture at 120° C. in an autoclave for 90 minutes.Sample 21B was a putty made from 5.18 g of carrier, 4.0 g of active DBM,and 4.71 mL of water. The carrier was made by mixing a 1:10 ratio of DBMand 0.05 N HCl, and heating the mixture at 55° C. in an autoclave for 90minutes. Sample 21C was a wet carrier made from 9.18 g of carrier and4.71 mL of water. The carrier was made by mixing a 1:10 ratio of DBM and0.05 N HCl, and heating the mixture at 120° C. in an autoclave for 90minutes. Sample 21D was a wet carrier made from 9.18 g of carrier and4.71 mL of water. The carrier was made by mixing a 1:10 ratio of DBM and0.05 N HCl, and heating the mixture at 55° C. in an autoclave for 90minutes. Sample 21E was a putty made from 2.67 g of carrier, 4.23 g ofactive DBM, and 14 mL of water. The carrier was a commercially availablefine porcine gelatin carrier. Sample 21F was a putty made from 2.67 g ofcarrier, 4.23 g of active DBM, and 14 mL of water. The carrier was acommercially available coarse porcine gelatin carrier. Sample 21G was awet carrier made from 6.9 g of carrier and 14 mL of water. The carrierwas a commercially available fine porcine gelatin carrier. Sample 21Hwas a putty made from 5.18 g of carrier, 4.0 g of active DBM, and 4.71mL of water. The carrier was made by mixing a 1:10 ratio of DBM and 0.05N HCl, and heating the mixture at 100° C. in an autoclave for 90minutes. Sample 211 was a wet carrier made from 9.18 g of carrier and4.71 mL of water. The carrier was made by mixing a 1:10 ratio of DBM and0.05 N HCl, and heating the mixture at 100° C. in an autoclave for 90minutes.

The test was carried out as using a Brookfield SST 2000 Soft SolidsTester (“SST 2000”). Samples 21A-21I were placed in the SST 2000. TheSST 2000 applied a constant, low stress to the samples. The SST 2000maintained that stress for a period of 60 seconds and then released thestress. The samples' response to stress (how far and how fast it moves)was plotted as a function of time. Another plot was created byextrapolating the straight-line steady-shear portion down to the strainaxis. This gave a certain strain value that describes the eventualequilibrium extension of the elastic elements present. The equilibriumstrain was then compared to the total strain to obtain anelastic/viscous ratio or elasticity index for the samples.

FIGS. 4A through 4D set forth dynamic viscosity analyses of Samples 21Aand 21C prepared as described above. FIGS. 4A and 4B relate to Sample21A. FIGS. 4C and 4D relate to Sample 21C. Results of dynamic viscositytesting are also shown in Table 4 below. As can be seen from theseresults, only the putty and carrier made by heating DBM at a temperatureof 120° C. for 90 minutes (Samples 21A and 21C) resulted in a measurabledynamic viscosity. The dynamic viscosity of Samples 21B and 21D through21I could not be measured using this test procedure because they formedgelatins and gelatins do not have a measurable dynamic viscosity.

TABLE 4 Results of Dynamic Viscosity Testing Creep Viscosity Creep RateElastic Sample (Pas) Shear Rate (1/s) (rad/s) Index 21A 38428.102 0.00470.00006 0.531  21B No Result No Result No Result No Result 21C 10826.62 0.0167 0.00022 0.5586 21D No Result No Result No Result No Result 21E NoResult No Result No Result No Result 21F No Result No Result No ResultNo Result 21G No Result No Result No Result No Result 21H No Result NoResult No Result No Result 21I No Result No Result No Result No Result

EXAMPLE 22

In this example, a kit comprising an osteoinductive putty was made. DBMwas separated into two portions: “Carrier DBM” and “Active DBM”. The“Carrier DBM” was used to make carrier according to Example 1 and isthen lyophilized and stored.

Lyophilized carrier made according to Example 1 was removed from thecontainer in which it was lyophilized. The carrier was placed in ablender pitcher being sure not to fill past the top of the black bladedevice. A lid was placed on the pitcher and tightly sealed all the wayaround. The blender was pulsed for 10 seconds at a speed of 7500 rpm.After pausing for 10 seconds, the blender was pulsed again for 10seconds, followed by an additional 10 second pause and 10 second pulse.

The carrier from the pitcher was placed into a 850 μm sieve. Carrierpassing through the sieve was collected. 10.4 g carrier was transferredfrom the collecting pan into a mixing bowl. 8.0 g of ‘active DBM’ wascombined with the carrier in a mixing bowl and mixed with a spoonulauntil evenly mixed.

The syringes for the putty and the equipment for loading the putty intothe syringes were prepared before combining the mixture with water. Theplunger of the loading dispenser was removed, and the final productsyringes were prepared for loading. This reduced the exposure of theputty to open air so as to avoid moisture loss.

14.31 ml sterile water was placed in a bowl, and the combination of DBMand carrier was poured into the bowl containing water. The water, DBMand carrier were mixed immediately using a spoonula. A firm steadykneading motion was used in order to fully press the water into themixture. The water was spread evenly throughout the putty, with no drypockets remaining in the putty. Once all powder was evenly wet (powdertends to darken visibly with wetting), the putty was gathered togetherinto one large piece.

The spoonula was used to collect the putty and to place it into theloading dispenser barrel. The loading dispenser plunger was insertedback into the barrel of the loading dispenser. The loading dispenserbore tip was placed into the barrel of a syringe, and an amount of putty(0.5 cc, 1 cc, 2 cc, or 5 cc) was extruded into syringes of appropriatesizes (1 cc, 3 cc, and 5 cc), just above the 0.5 cc, 1 cc, 2 cc, or 5 ccvolume indicator on the appropriate syringes. The product volume wasassessed using the increments marked on the syringe. The loadingdispenser was removed, and the syringe plunger was placed back into thesyringe barrel. The syringe was checked to ensure that under the plungerthere was still 0.5 cc, 1 cc, 2 cc, or 5 cc of putty. The 1 cc syringewas capped with a screw-on cap, and the 3 cc and 5 cc syringes werecapped by pressing the silicone cap firmly on the syringe barrel untilsecure. The caps were firmly secured onto the syringe. The putties aresealed in the capped syringes.

The filled syringe was inserted into a clearfoil (inner) pouch. Theclearfoil pouch was placed in an Accu-Seal Model 730 Medical Sealer.Once the sealing cycle was complete, the pouch was removed from thesealer, and a barcode was added for product tracking. The clearfoilpouch was placed in a tyvek (outer) pouch with chevron seals on the sameside.

EXAMPLE 23

In this example, the osteoinductive potential of several embodiments ofthe present osteoinductive putty was evaluated in a Urist (rat ectopicpouch) model, as well as the inflammatory response of the rats to theseputties. The osteoinductivity and inflammation scores of the puttieswere compared to scores from implanting DBM alone.

As a starting material, four DBM samples were provided which had beenobtained from four different donors. These DBM samples had beenpreviously scored for osteoinductivity and inflammation by an athymicnude rat assay. Previous scoring was completed on these samples of DBMplus porcine gelatin. These previous scores were used to select thetreatment groups for this example. For example, one treatment group wasto be implanted with DBM sample that scored a 2 for osteoinductivity anda 1 for inflammation when tested with a porcine gelatin. DBM sample fromone donor that previously scored 2.1, and three donors that previouslyscored 3.1 were selected for use in this example. Samples that hadpreviously scored 0.1 and 4.1 were also used in this example ascontrols.

Carrier was prepared from the starting DBM as described in Example 1.The final formulations of the putties were prepared as described inExample 8. All donor material was processed in a controlled productionenvironment by bone paste processors using conventional methods of DBMpreparation. Samples were prepared in accordance with Table 5. Puttysamples were packed into 1 cc sterile syringes. The DBM controls werepacked in sterile vials. All samples were packaged in foil-foil pouchesand were sent for irradiation at a dosage of 25-31 kGy.

After irradiation, the samples were implanted in athymic nude rats inaccordance with the following procedures. Each rat was implanted with adifferent sample at six different sites in the ventral abdominal muscle(sites A through F on each rat). The rat subjects were anesthetized withketamine/xylazine. A mid-ventral incision (1 inch) was made from belowthe sternum to just above the groin area. The skin was lifted andbluntly dissected from the fascia. Any remaining fascia was snippedaway. The skin was clamped on one side, exposing the muscle. Theabdominal muscle was picked up 1-1.5 cm to the side of the midline (inthe recti abdomini). A 1-2 mm incision was made in the muscle pinched bya forceps. The tip of scissors was inserted laterally into the incisionin the muscle, and gently opened and closed to make a small pocket forthe sample. The peritoneal cavity was not penentrated.

The putty or DBM was dispensed directly into the appropriate musclepocket site. The muscle incision was sutured, and the procedure wasrepeated to implant putty or DBM in the other five sites in the ventraladmonimal muscle of the rat. All six implant sites were visually checkedto see that the implant was still in place, the stitch was secure, andthere were no visible problems relating to the surgery. The incision inthe rat's abdomen was then closed.

Each treatment was implanted in triplicate in three separate rats. Sixsamples were implanted per rat. The rats were sacrificed and theimplants were extracted after 28 days and the samples were prepared forhistological evaluation. All implanted material was carefully retrieved,and if no implant was visible, the muscle portion was removed wheresuture indicated implant was placed. The histological slides were scoredfor osteoinductivity and inflammatory responses as follows.

Each slide was examined under the microscope and rated forosteoinductivity. There were five slices per explant, and each slice wasindividually scored as follows: It was scored “0” if there was no signof new bone formation in any of the five slices of the explant. It wasscored “1” if up to 25% of the area of the explant slice was involved inbone formation. It was scored “2” if between 25 and 50% of the area ofthe explant slice is involved in bone formation. It was scored “3” ifbetween 50 and 75% of the area of the explant slice is involved in boneformation. It was scored “4” if between 75 and 100% of the area o f theexplant slice is involved in bone formation. Areas were considered to beinvolved in bone formation where they demonstrated evidence of new boneformation including chondrocytes, cartilage, marrow, and new bone.

Each slide to be rated for inflammation was examined under themicroscope. There were five slices per explant. Each slice wasindividually scored as follows. It was scored “1” if no multi-nucleatedgiant cell (MNGCs) were present, minimal fibrous connective tissue waslargely in the periphery of explant, and residual allograft(un-remodeled implant material) appeared intact or involved inremodeling. It was scored “2” if occasional MNGCs were observed,moderate fibrous connective tissue was present in the periphery andinterstitially, and residual allograft appeared intact or involved inremodeling. It was scored “3” if 50% or more of explant areademonstrated cellular infiltration largely characterized by MNGCs, densefibrous connective tissue filled the majority of the explant area, andresidual allograft was being resorbed and/or absent.

TABLE 5 Sample Categories and Treatments Starting Implanted Sample DBMMaterial Rat-Implant Location 23A Donor 1 Carrier & 1-A 4-B 3-C ActiveDBM 23B Donor 1 Active DBM 2-F 1-D 5-A Only 23C Donor 2 Carrier & 3-E2-C 1-C Active DBM 23D Donor 2 Active DBM 4-A 5-F 5-B Only 23E Donor 3Carrier & 4-C 2-B 3-A Active DBM 23F Donor 3 Active DBM 2-D 1-E 5-E Only23G Donor 4 Carrier & 5-C 1-B 2-E Active DBM 23H Donor 4 Active DBM 3-B3-D 4-D Only 23I Donor 5 DBM Only 4-F 2-A 3-F 23J Donor 6 DBM Only 1-F5-D 4-E

Table 6 sets forth the raw histology scores from each implant sample.

TABLE 6 Rat 1 Rat 2 Rat 3 OI OI OI Sample Treatment (% bone) MaturityInf (% bone) Maturity Inf (% bone) Maturity Inf 23A D1 Putty 2 (38) 7 12 (40) 8 1 3 (51) 8 1 23B D1 DBM 2 (45) 8 1 2 (42) 7 1 2 (43) 8 2 alone23C D2 Putty 3 (52) 8 1 2 (49) 8 1 2 (37) 7 1 23D D2 DBM 2 (43) 8 2 3(57) 9 1 2 (38) 8 1 alone 23E D3 Putty 2 (32) 8 2 3 (61) 9 2 3 (60) 9 223F D3 DBM 4 (76) 9 1 3 (59) 9 1 3 (68) 9 2 alone 23G D4 Putty 1 (15) 71 1 (22) 5 1 1 (20) 7 1 23H D4 DBM 1 (22) 7 1 2 (47) 8 1 2 (29) 8 1alone 23I D5 control 0 (0)  0 2 0 (0)  0 2 0 (0)  0 3 23J D6 DBM 4 (76)9 1 3 (58) 9 1 3 (60) 9 1 control

Table 7 sets forth the mean and the standard deviation of the histologyscores:

TABLE 7 Sample Treatment OI ± SD % Bone ± SD Maturity ± SD Inflammation± SD 23A D1 Putty 2.3 ± 0.58 43 ± 7  7.7 ± 0.58 1 ± 0 23B D1 DBM alone 2± 0  43.3 ± 1.5  7.7 ± 0.58  1.3 ± 0.58 23C D2 Putty 2.3 ± 0.58  46 ±7.9 7.7 ± 0.58 1 ± 0 23D D2 DBM alone 2.3 ± 0.58 46 ± 10 8.3 ± 0.58  1.3± 0.58 23E D3 Putty 2.7 ± 0.58 51 ± 16 8.7 ± 0.58 2 ± 0 23F D3 DBM alone3.3 ± 0.58 67.7 ± 8.5  9 ± 0   1.3 ± 0.58 23G D4 Putty 1 ± 0   19 ± 3.66.3 ± 1.2  1 ± 0 23H D4 DBM alone 1.7 ± 0.58 32.7 ± 12.9 7.7 ± 0.58 1 ±0 23I D5 control 0 ± 0  0 ± 0 0 ± 0   2.3 ± 0.58 23J D6 control 3.3 ±0.58 64.7 ± 9.9  9 ± 0  1 ± 0

The addition of the carrier to the active DBM did not unduly affect theOI results of the putties compared to the DBM alone. In addition, therewas no significant affect in the bone maturity scores of the puttiesrelative to the DBM alone. Although the sample size was small (n=4donors), this data suggests that there is no difference betweenindividual donors in the fact that the addition of the carrier to theactive DBM did not unduly affect the results. As expected, the OI scorefor the negative control (0.1 DBM) samples was zero as was the bonematurity score. The OI score for the positive control was in the 3-4range with a bone maturity score of 9.

As shown in Tables 6 and 7, the putty samples (Samples 23A, 23C, 23E and23G) compared favorably to the DBM alone samples (Samples 23B, 23D, 23Fand 23H) with respect to inflammation scores. The addition of thecarrier to the DBM did not result in inflammation scores that would berejected (to avoid rejection, at least 2 of 3 samples from each donormust receive an inflammatory score equal to or less than 2).

Only one sample (Donor 3, Samples 23E and 23F) generated an inflammatoryscore of 2 in all three rats. One sample from Donor 1, Donor 2, andDonor 3 had an inflammatory score of 2. As noted above, all the samplestested would be passed by the relevant inflammatory scoring protocol.The other test samples within each of these treatment groupsdemonstrated inflammatory scores of 1. The deactivated DBM control(Donor 5, sample 231) generated an inflammatory that would be rejectedby the current RTI inflammatory scoring protocol and this has beenobserved in the past.

This example demonstrates that the present osteoinductive putty iseffective at inducing new both growth in the subjects in which it wasimplanted. It also demonstrates that the present osteoinductive puttiesgenerally did not generate an excessive inflammatory response in thesubjects.

In the present specification, use of the singular includes the pluralexcept where specifically indicated. The use of the terms “a” and “an”and “the” and similar referents in the context of describing theinvention (especially in the context of the following claims) are to beconstrued to cover both the singular and the plural, unless otherwiseindicated herein or clearly contradicted by context. The terms“comprising,” “having,” “including,” and “containing” are to beconstrued as open-ended terms (i.e., meaning “including, but not limitedto,”) unless otherwise noted. Whenever the term “about” appears before avalue, it should be understood that the specification is also providinga description of that value apart from the term “about”. Wherever anopen-ended term is used to describe a feature or element of theinvention, it is specifically contemplated that a closed-ended term canbe used in place of the open-ended term without departing from thespirit and scope of the invention. Recitation of ranges of values hereinare merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. The use ofany and all examples, or exemplary language (e.g., “such as”) providedherein, is intended merely to better illuminate the invention and doesnot pose a limitation on the scope of the invention unless otherwiseclaimed. No language in the specification should be construed asindicating any non-claimed element as essential to the practice of theinvention.

In the present specification, any of the functions recited herein may beperformed by one or more means for performing such functions. Withrespect to the methods described in the specification, it is intendedthat the specification also provides a description of the products ofthose methods. With respect to the compositions and combinationsdescribed in the specification, it is intended that the specificationalso provides a description of the components, parts, portions, of suchcompositions and combinations.

All of the references cited herein, including patents, patentapplications, and publications, are hereby incorporated in theirentireties by reference.

While particular elements, embodiments and applications of the presentinvention have been shown and described, it will be understood, ofcourse, that the invention is not limited thereto since modificationscan be made by those skilled in the art without departing from the scopeof the present disclosure, particularly in light of the foregoingteachings.

Although the dependent claims have single dependencies in accordancewith U.S. patent practice, each of the features in any of the dependentclaims can be combined with each of the features of other dependentclaims or the main claim.

We claim:
 1. An osteoinductive putty comprising: an osteoinductivesubstance, and a carrier comprising a mixture of collagen fragmentshaving a substantially uniform molecular weight distribution within therange of from about 45 kDa to about 66 kDa. 2-20. (canceled)